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Travel_Word_Problems/674406: At noon, a jetliner left New York for Los Angeles 4000 kn away. At 1:00 P.M. New York time a jetliner, flying 10 km/hr faster than the first one, left Los Angeles for New York. The planes passed each other at 3:00 P.M.New York time. Find the speed of the planes.

1 solutions

Answer 419217 by josmiceli(9664) About Me  on 2012-10-31 17:54:49 (Show Source):
You can put this solution on YOUR website!
Let the speed of the NY_LA plane = +s+
The NY-LA plane got a head start of +s%2A1+ km
The planes were then +4000+-+s+ km apart
Let +d+ = distance in km that the NY-LA plane
has to travel until it meets the LA-NY plane
----------------------
NY-LA plane's equation:
(1) +d+=+s%2A2+ ( note that time starts at 1 PM and ends at 3 PM )
LA-NY plane's equation:
(2) +4000+-+s+-+d+=+%28+s+%2B+10+%29%2A2+
------------------------------
Substitute (1) into (2)
(2) +4000+-+s+-+2s+=+%28+s+%2B+10+%29%2A2+
(2) +4000+-+3s+=+2s+%2B+20+
(2) +5s+=+4000+-+20+
(2) +5s+=+3980+
(2) +s+=+796+
+s+%2B+10+=+806+
The speeds of the planes are:
NY-LA - 796 km/hr
LA-NY - 806 km/hr
-----------------
check answer:
(1) +d+=+s%2A2+
(1) +d+=+796%2A2+
(1) +d+=+1592+ km
and
(2) +4000+-+s+-+d+=+%28+s+%2B+10+%29%2A2+
(2) +4000+-+796+-+d+=+806%2A2+
(2) +3204+-+d+=+1612+
(2) +d+=+3204+-+1612+
(2) +d+=+1592+ km
OK


percentage/674390: The Carcharodon megaladon shark of the Miocene ere is believed to have been about 12 meters long.The modern great white shark is about 6 meters long.Write the change in length of these longest sharks over time as a percent increase or decrease.
1 solutions

Answer 419208 by josmiceli(9664) About Me  on 2012-10-31 17:17:14 (Show Source):
You can put this solution on YOUR website!
The change in length is +12+-+6+=+6+ m
The percent decrease in length is
+%286+%2F+12%29%2A100+=+50+
50% decrease


Linear_Algebra/674383: how do you substitute:
3u + 8 = 4v
24v = 6 - 3u
1 solutions

Answer 419207 by josmiceli(9664) About Me  on 2012-10-31 17:13:29 (Show Source):
You can put this solution on YOUR website!
(1) +3u+%2B+8+=+4v+
(2) +24v+=+6+-+3u+
------------------
(2) +24v+-+6+=+-3u+
(2) +-24v+%2B+6+=+3u+
Substitute +3u+ in (2) in place
of +3u+ in (1)
(1) +-24v+%2B+6+%2B+8+=+4v+
(1) +28v+=+14+
(1) +v+=+1%2F2+
Plug this back into (1)
(1) +3u+%2B+8+=+4%2A%281%2F2%29+
(1) +3u+=+2+-+8+
(1) +3u+=+-6+
(1) +u+=+-2+


Linear-equations/674382: Which equation represents a line that passes through the points (-3,2) and (1,10)
1 solutions

Answer 419205 by josmiceli(9664) About Me  on 2012-10-31 17:05:45 (Show Source):
You can put this solution on YOUR website!
Use the general point-slope formula
+%28+y+-+2+%29+%2F+%28+x+-+%28-3%29+%29+=+%28+10+-+2+%29+%2F+%28+1+-+%28-3%29+%29+
++%28+y+-+2+%29+%2F+%28+x+%2B+3+%29+=+8+%2F+4+
+%28+y+-+2+%29+%2F+%28+x+%2B+3+%29+=+2+
+y+-+2+=+2%2A%28+x+%2B+3+%29+
+y+-+2+=+2x+%2B+6+
+y+=+2x+%2B+8+
---------------
check answer:
(-3,2)
+2+=+2%2A%28-3%29+%2B+8+
+2+=+-6+%2B+8+
+2+=+2+
(1,10)
+10+=+2%2A1+%2B+8+
+10+=+10+
OK


percentage/674371: Mr.Simmons owns a hardware store and typically marks up merchandise by 28% over warehouse cost.How much would he charge for a hammer that costs him $13.50?
1 solutions

Answer 419203 by josmiceli(9664) About Me  on 2012-10-31 17:00:00 (Show Source):
You can put this solution on YOUR website!
+13.50+%2B+.28%2A13.5+=+1.28%2A13.5+
+1.28%2A13.5+=+17.28+
He charges $17.28


Rate-of-work-word-problems/674348: If 7 guys take 8 days to build a trench, how many guys will it take to build the trench in 1/2 day?
1 solutions

Answer 419201 by josmiceli(9664) About Me  on 2012-10-31 16:57:01 (Show Source):
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7 guys take 8 days for 1 trench
It takes 8 times as may guys to do 1
trench in 1/8 of that time, or 1 day, so
It takes 56 guys 1 day to do 1 trench
To do it in 1/2 that time will take twice as many guys
112 guys can do 1 trench in 1/2 day


Rate-of-work-word-problems/674345: anthony can build a wall in 10 hours. his helper can do it in 15 hours. how long will it take them working together, assuming that each works at his own rate?

1 solutions

Answer 419170 by josmiceli(9664) About Me  on 2012-10-31 15:16:45 (Show Source):
You can put this solution on YOUR website!
Add their rates of working
Anthony's rate is ( 1 wall ) / ( 10 hrs )
Helper's rate is ( 1 wall ) / ( 15 hrs )
Let +t+ = time in hours for them to do it together
+1%2F10+%2B+1%2F15+=+1%2Ft+
Multiply both sides by +30t+
+3t+%2B+2t+=+30+
+5t+=+30+
+t+=+6+
It takes them 6 hrs working together


Miscellaneous_Word_Problems/674341: Find two consecutive positive integers such that the sum of their squares is 145.
1 solutions

Answer 419169 by josmiceli(9664) About Me  on 2012-10-31 15:12:04 (Show Source):
You can put this solution on YOUR website!
Let the consecutive integers be +n+ and +n+%2B+1+
given:
+n%5E2+%2B+%28+n+%2B+1+%29%5E2++=+145+
+n%5E2+%2B+n%5E2+%2B+2n+%2B+1+=+145+
+2n%5E2+%2B+2n+-+144+=+0+
+n%5E2+%2B+n+-+72+=+0+
I can see that this is
+%28+n+%2B+9+%29%2A%28+n+-+8+%29+=+0+
+n+=+8+ is the positive answer
+n+%2B+1+=+9+
The numbers are 8 and 9
check:
+8%5E2+%2B+9%5E2+=+64+%2B+81+
+64+%2B+81+=+145+
OK


Quadratic_Equations/674342: What is the y intercept of the function y=4x²-1?
1 solutions

Answer 419168 by josmiceli(9664) About Me  on 2012-10-31 15:05:46 (Show Source):
You can put this solution on YOUR website!
The y-intercept is where +x=0+,so
+y+=+4%2A0%5E2+-1+
+y+=+-1+
the answer is (0,-1)


Expressions-with-variables/674338: A goes down river 9 miles, then back upriver for 3 miles. Rate of river current is 6 mph. How long does it take A to go the 12 miles? I have 9/x-6 for time downstream, and 3/x-6 for time upstream, but don't know how to set up the equation. (Answer is 1 hour.)
1 solutions

Answer 419167 by josmiceli(9664) About Me  on 2012-10-31 15:03:53 (Show Source):
You can put this solution on YOUR website!
let +r+ = A's rate in still water ( no current )
Going downstream, his rate is +r+%2B+6+
Going upstream, his rate is +r+-+6+
---------------
Going downstream,
+9+=+%28+r+%2B+6+%29%2At%5B1%5D+
Going upstream,
+3+=+%28+r+-+6+%29%2At%5B2%5D+
-------------------
You need to find +t%5B1%5D+%2B+1%5B2%5D+
+t%5B1%5D+=+9+%2F+%28+r+%2B+6+%29+
+t%5B2%5D+=+3+%2F+%28+r+-+6+%29+
--------------------
+t%5B1%5D+%2B+t%5B2%5D+=+9%2F%28+r+%2B+6+%29+%2B+3%2F%28+r+-+6+%29+
I think you're missing his rate in still water
Can't solve without it.




Polynomials-and-rational-expressions/674037: tring to figue out how to do this problem (3x to the 2nd power-6x+8)+(2x to the 2nd power+2x-6) can you show me how to do this problem

1 solutions

Answer 419164 by josmiceli(9664) About Me  on 2012-10-31 14:49:52 (Show Source):
You can put this solution on YOUR website!
Is this it?
+%28+3x%5E2+-+6x+%2B+8+%29+%2B+%28+2x%5E2+%2B+2x+-+6+%29+
If so, you need to combine the like terms and then add everything
+%28+3x%5E2+%2B+2x%5E2+%29+%2B+%28+-6x+%2B+2x+%29+%2B+%28+8+-+6+%29+
+5x%5E2+-+4x+%2B+2+ answer


percentage/674047: In June, Lindsey purchased an airfare ticket for $450 from Dallas to New York City. In July, the airline reduced the fare to $360. What percent is the reduction? (Please solve in percent decrease formula, i got 92% but im not sure i was absent yesterday and this is my make up work)
1 solutions

Answer 419013 by josmiceli(9664) About Me  on 2012-10-30 21:27:18 (Show Source):
You can put this solution on YOUR website!
The dollar amount of the reduction is
+450+-+360+=+90+
The percent reduction is
+%2890%2F450%29%2A100+=+20+
20%


Travel_Word_Problems/673883: Two trains, one express and one local, leave Indianapolis at noon and head for Chicago 220 miles away. The express travels twice as fast as the local and arrives 2 hours ahead of the local. Find the speed of each train
1 solutions

Answer 418921 by josmiceli(9664) About Me  on 2012-10-30 16:46:07 (Show Source):
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Let +s+ = the speed of the local train
Let +t+ = the travel time for the local train
-----------
Equation for local train:
(1) +220+=+s%2At+
Equation for express train:
(2) +220+=+2s%2A%28+t+-+2+%29+
----------------------
(2) +220+=+2%2As%2At+-+4s+
Substitute (1) into (2)
(2) +220+=+2%2A220+-+4s+
(2) +4s+=+440+-+220+
(2) +4s+=+220+
(2) +s+=+55+
+2s+=+110+
The express train's speed is 110 m,i/hr
The local train's speed is 55 mi/hr
check answer:
(1) +220+=+s%2At+
(1) +t+=+220%2F55+
(1) +t+=+4+
and
(2) +220+=+2s%2A%28+4+-+2+%29+
(2) +220+=+4s+
(2) +s+=+55+
OK







Square-cubic-other-roots/673723: I am really struggling when the 'power' is either a fraction, a decimal or a square root. For example 5^1.9 or 4^square root of 6.
5^1 would be 5^2 would be 25, so logic would tell me since 1.9 is slightly less than 2, the number would be less than the 25, but I have no idea how to work these. I know in the other example the square root of 6 is 2.44, so that should tell me that it would be equal to 4^2.44, but again, while 4^2 is 16, I think the answer would be greater than that, but do not know how to do the math! All help would be tremendously appreciated. I have gone back to school after a 35 year absence and math is giving me problems.
1 solutions

Answer 418849 by josmiceli(9664) About Me  on 2012-10-30 12:30:38 (Show Source):
You can put this solution on YOUR website!
Basically, the answer is that you follow the
normal rules that you know when dealing
with whole numbers.
You are right that it's hard to get a feel for
what something like +3%5E1.05+ means,
but all you can do is apply rules that you know, like
(1) +a%5Eb+%2A+a%5Ec+%2A+a%5Ed+=+a%5E%28%28+b+%2B+c+%2B+d+%29%29+ and
(2) +%28a%5Eb%29%5Ec+=+a%5E%28%28b%2Ac%29%29+ and
(3) +a%5E%28-b%29+=+1%2F%28a%5Eb%29+
---------------------
You can always convert decimals to fractions, too, if it helps
+7%5E6.5+=+7%5E%28+2%2B2%2B2%2B.5+%29+, and using rule (1) backwards,
+7%5E6.5+=+7%5E2+%2A+7%5E2+%2A+7%5E2+%2A+7%5E%281%2F2%29+
+7%5E6.5+=+49+%2A+49+%2A+49+%2A+sqrt%28+7+%29+
+7%5E6.5+=+49%5E3+%2A+sqrt%287%29+
You could do this on a calculator that only has +,-,x, and square root
like the one I'm using
---------------------
If you have +3%5E%28+-.001+%29+ , follow rule (3)
+1+%2F+3%5E%28.001%29+
Note that +.001+=+1%2F1000+ , so you have
+1+%2F+root+%28+1000%2C3+%29+
The 1000th root of 3 is probably a little more than 1, so
the fraction 1/1.0+ should be a little less than 1
----------------------
Hope some of this helps




Average/673585: what is nCn. please i need help. my math teacher hates me!!!!!!!!!!!!!!!!!!!!!!!!!!
1 solutions

Answer 418723 by josmiceli(9664) About Me  on 2012-10-29 22:27:56 (Show Source):
You can put this solution on YOUR website!
With combinations, you don't care about the order
of the things being counted.
Suppose +n+=+10+
+10C10+ is the combination of 10 things taken
10 at a time. There is only 1 of these, since you're
looking at all 10 of the things.The same is true no matter what n is


Probability-and-statistics/673571: please help me!!!!
if 3 fair coins are tossed, find the probability of each number of heads.
1) 0
2) 2
3) 1 or 2
1 solutions

Answer 418722 by josmiceli(9664) About Me  on 2012-10-29 22:22:01 (Show Source):
You can put this solution on YOUR website!
It helps if you write down all the possible outcome
H H H
T T T
H H T
H T H
T H H
T T H
T H T
H T T
There are 8 possible outcomes, which is +2%2A2%2A2+=+8+
(1)
no heads. Only T T T fits, so
P( 0H ) = 1/8
---------------
(2)
Exactly 2 heads. There are 3 of these, so
P( 2H ) = 3/8
---------------
(3)
Exactly 1 head or exactly 2 heads. When you see OR, you
add the separate probabilities
P( 1H ) = 3/8
P( 1H ) + P( 2H ) = 3/8 + 3/8
3/8 + 3/8 = 3/4


Rate-of-work-word-problems/673552: Justin starts at a point 26 miles from home and runs toward home at 6 mph. Rhonda starts from home 1.3 hours later and pedals toward Justin at 8 mph. How long has Justin been running when he meets Rhonda? How far from home do they meet?
1 solutions

Answer 418717 by josmiceli(9664) About Me  on 2012-10-29 22:04:31 (Show Source):
You can put this solution on YOUR website!
Justin gets a head start of
+6%2A1.3+=+7.8+ mi
They are then +26+-+7.8+=+18.2+ mi apart
----------------
Let +d+ = the distance Rhonda now has
to cover to meet Justin.
+18.2+-+d+ = distance Justin now has to cover
Let +t+ = the time it now takes them to meet
------------
After Justin's head start:
Justin's equation:
(1) +18.2+-+d+=+6t+
Rhonda's equation:
(2) +d+=+8t+
-------------
Substitute (2) into (1)
(1) +18.2+-+8t+=+6t+
(1) +14t+=+18.2+
(1) +t+=+1.3+ hrs
and
(1) +18.2+-+d+=+6%2A1.3+
(1) +18.2+-+d+=+7.8+
(1) +d+=+18.2+-+7.8+
(1) +d+=+10.4+
Justin has been running for +1.3+%2B+1.3+=+2.6+ hrs
Rhonda travels +d+=+10.4+ mi from home
where they meet







Linear_Equations_And_Systems_Word_Problems/673452: a health club charges a one time fee of $99 and then $39 per month for membership. Let m represent the number of months, and let C represent the total amount of money spent on the health club membership write an equation that relates m and C
1 solutions

Answer 418692 by josmiceli(9664) About Me  on 2012-10-29 19:51:42 (Show Source):


Numeric_Fractions/673457: Please help me solve this problem 9 over 14 x 7 over 9

1 solutions

Answer 418677 by josmiceli(9664) About Me  on 2012-10-29 18:47:56 (Show Source):
You can put this solution on YOUR website!
+%289%2F14%29%2A%287%2F9%29+
Numbers on the bottom can be moved around
when multiplying, as long as they stay on the bottom,
so you can rewrite it this way:
+%289%2F9%29%2A%287%2F14%29+
Note that +9%2F9+=+1+, so now you have
+7%2F14+
You can rewrite this as:
+7%2F%28+7%2A2+%29+
and again as:
+%287%2F7%29%2A%281%2F2%29+ and since +7%2F7+=+1+
+1%2A%281%2F2%29+=+1%2F2+


Travel_Word_Problems/673461: Jim was driving to work.He drives 50 miles in 60 minutes.How fast was he going?
1 solutions

Answer 418675 by josmiceli(9664) About Me  on 2012-10-29 18:42:24 (Show Source):
You can put this solution on YOUR website!
60 minutes = 1 hr
so, he was going 50 mi/hr


Travel_Word_Problems/673077: During the first 6 hours of a trip, you average 44 mi/h. During the last 4 hours of your trip, your average 50 mi/h. What is your average speed for the entire trip?
1 solutions

Answer 418476 by josmiceli(9664) About Me  on 2012-10-28 22:13:27 (Show Source):
You can put this solution on YOUR website!
Average speed is always
( total distance ) / ( total time )
for 1st 6 hrs:
+d+=+44%2A6+
+d+=+264+ mi
--------------
For the last 4 hrs:
+d+=+50%2A4+
+d+=+200+ mi
--------------
The average speed is:
+%28+264+%2B+200+%29+%2F+10+
+464+%2F+10+
+46.4+ mi/hr


Linear-equations/673083: What is x and y in this problem 3x +8y =101
1 solutions

Answer 418475 by josmiceli(9664) About Me  on 2012-10-28 22:06:52 (Show Source):
You can put this solution on YOUR website!
It can't be solved
You need 1 equation if you have 1 unknown
You need 2 equations if you have 2 unknowns
You need 3 equations if you have 3 unknowns
You need 4 equations if you have 4 unknowns
You need 5 equations if you have 5 unknowns
etc.


Square-cubic-other-roots/673041: For some reason this still isn't clicking ....
homework problem finding the square root sets:
3(x+3)^2 = 36
Hellppp :(
1 solutions

Answer 418448 by josmiceli(9664) About Me  on 2012-10-28 20:58:41 (Show Source):
You can put this solution on YOUR website!
+3%28x%2B3%29%5E2+=+36+
I can say +3+=+%28+sqrt%283%29+%29%5E2+
+%28+sqrt%283%29+%29%5E2%2A%28+x%2B3+%29%5E2+=+36+
+%28+sqrt%283%29+%2A%28+x%2B3+%29%29%5E2+=+36+
Take the square root of both sides
(1) +sqrt%283%29%2A%28+x+%2B+3+%29+=+6+
+x+%2B+3+=+2%2A%28+3%2Fsqrt%283%29+%29+
+x+=+3+=+2%2Asqrt%283%29+
+x+=+-3+%2B+2%2Asqrt%283%29+
---------------------
Now go back to (1) and take the negative square root
of the right side
(1) +sqrt%283%29%2A%28+x+%2B+3+%29+=+-6+
+x+%2B+3+=+-2%2A%28+3%2Fsqrt%283%29+%29+
+x+=+-3+-+2%2Asqrt%283%29+
---------------------
You can plug both these results back into
the original problem





Rectangles/672940: The area is 4700 square feet. The length is twice the width minus six feet. I need help setting up the problem and solving it.
1 solutions

Answer 418409 by josmiceli(9664) About Me  on 2012-10-28 16:41:18 (Show Source):
You can put this solution on YOUR website!
Let The width = +w+ ft
You are given that the length = +2w+-+6+ ft
Let area = +A+
+A+ = length x width
+A+=+w%2A%28+2w+-+6+%29+ ft2
You are given that +A+=+4700+ ft2
+4700+=+w%2A%28+2w+-+6+%29+
+4700+=+2w%5E2+-+6w+
+2w%5E2+-+6w+-+4700+=+0+
Divide both sides by +2+

+a+=+1+
+b+=+-3+
+c+=+-2350+
+w+=+%28-%28-3%29+%2B-+sqrt%28+%28-3%29%5E2+-+4%2A1%2A%28-2350%29+%29%29+%2F+%282%2A1%29+
+w+=+%28+3+%2B-+sqrt%28+9+%2B+9400+%29%29+%2F+2+
+w+=+%28+3+%2B-+sqrt%28+9409+%29%29+%2F+2+
+w+=+%28+3+%2B+97+%29+%2F+2+ ( ignore the negative square root of 9409 )
+w+=+100%2F2+
+w+=+50+
+2w+-+6+=+2%2A50+-+6+
+2w+-+6+=+94+
The width is 50 ft and
the length is 94 ft
-------------------
check:
+A+=+50%2A94+
+A+=+4700+
OK


test/672830: Josh was in charge of bringing bags of chips to a homecoming party the doritos cost $1.79 per bag and the cheetos cost $2.01 per bag he bought 15 bags of chips together how many of each type did he buy if he spent a total of $28.17?
1 solutions

Answer 418334 by josmiceli(9664) About Me  on 2012-10-28 11:49:02 (Show Source):
You can put this solution on YOUR website!
Let +a+ = bags of Doritos bought
Let +b+ = bags of Cheetos bought
given:
(1) +a+%2B+b+=+15+
(2) +1.79a+%2B+2.01b+=+28.17+
---------------------------
(2) +179a+%2B+201b+=+2817+
Multiply both sides of (1) by +179+
and subtract (1) from (2)
(2) +179a+%2B+201b+=+2817+
(1) +-179a+-+179b+=+-2685+
+22b+=+132+
+b+=+6+
and
(1) +a+%2B+6+=+15+
(1) +a+=+9+
9 bags of Doritos were bought
6 bags of Cheetos were bought
check:
(2) +1.79%2A9+%2B+2.01%2A6+=+28.17+
(2) +16.11+%2B+12.06+=+28.17+
(2) +28.17+=+28.17+
OK


Travel_Word_Problems/672809: During rush hour, Fernando can drive 25 miles using the side roads in the same time that it takes to travel 20 miles on the freeway. If Fernando's rate on the side roads is 9 mi/h faster than his rate on the freeway, find his rate on the side roads?
1 solutions

Answer 418330 by josmiceli(9664) About Me  on 2012-10-28 11:31:02 (Show Source):
You can put this solution on YOUR website!
Let +r+ = his rate on the freeway
+r+%2B+9+ = his rate on side roads
Let +t+ = time for both
----------
On side roads:
(1) +25+=+%28+r+%2B+9+%29%2At+
On freeway:
(2) +20+=+r%2At+
---------------
(1) +25+=+r%2At+%2B+9t+
Substitute (2) into (1)
(1) +25+=+20+%2B+9t+
(1) +9t+=+5+
(1) +t+=+5%2F9+
--------------
On side roads:
(1) +25+=+%28+r+%2B+9+%29%2A%285%2F9%29+
(1) +25+=+%285%2F9%29%2Ar+%2B+5+
(1) +%285%2F9%29%2Ar+=+20+
(1) +r+=+%289%2F5%29%2A20+
(1) +r+=+36+
+r+%2B+9+=+45+
His rate on side roads is 45 mi/hr
check:
(2) +20+=+r%2At+
(2) +20+=+36%2A%285%2F9%29+
(2) +180+=+180+



Evaluation_Word_Problems/672812: The following formula models the number of prison inmates, P, in thousands who are in US prisons x years after 1980.
P=2x^2+20x+328
Find the first year in which the population of US prisons was approximately 440,000 people.
Thank you for your help
1 solutions

Answer 418321 by josmiceli(9664) About Me  on 2012-10-28 11:00:01 (Show Source):
You can put this solution on YOUR website!
+P+ is in thousands, so
+440+=+2x%5E2+%2B+20x+%2B+328+
+2x%5E2+%2B+20x+-+112+=+0+
x%5E2+%2B+10x+-+56+=+0+
Complete the square
+x%5E2+%2B+10x+%2B+%2810%2F2%29%5E2+=+56+%2B+%2810%2F2%29%5E2+
+x%5E2+%2B+10x+%2B+25+=+56+%2B+25+
+%28+x+%2B+5+%29%5E2+=+81+
+x+%2B+5+=+9+
+x+=+4+
The year is 1984


test/672714: 3{ [4 (x-1) +5] - [ 2 ( 2x-1) +5]}
i know "pemdas", but i cant figure this out. I dont get when to apply the distributive law, and how this cancles out. I guess the order us messing me up.
1 solutions

Answer 418269 by josmiceli(9664) About Me  on 2012-10-27 22:02:32 (Show Source):
You can put this solution on YOUR website!
Always work from the inside out
+3%2A%28+%28+4%2A%28x-1%29+%2B+5+%29+-+%28+2%2A%28+2x-1+%29+%2B+5+%29%29+
One check that you can do is just count the
number of ( 's and the number of ) 's -they
should be the same. In this problem, they
both are 5.
------------
first step:
+3%2A%28+%28+4x+-+4+%2B+5+%29+-+%28+4x+-+2+%2B+5+%29%29+
Now simplify:
+3%2A%28%28+4x+%2B+1+%29+-+%28+4x+%2B+3+%29%29+
The +4x+%2B+1+ doesn't really need to be in
parentheses at this point, also, do the
subtraction using distributive law.
+3%2A%28+4x+%2B+1+-+4x+-+3+%29+
+3%2A%28+-2+%29+
+-6+
Note that it doesn't matter what +x+ is,
the result is still +-6+


Linear_Equations_And_Systems_Word_Problems/672706: Julio has found that his new car gets 36 miles per gallon on the highway
and 31 miles per gallon in the city. He recently drove 397 miles on 12
gallons of gasoline. How many miles did he drive on the highway? How
many miles did he drive in the city?
1 solutions

Answer 418266 by josmiceli(9664) About Me  on 2012-10-27 21:46:44 (Show Source):
You can put this solution on YOUR website!
( miles/gallon ) x ( gallons used ) = miles driven
Let +a+ = gallons used on highway
Let +b+ = miles driven on highway
On highway:
(1) +36a+=+b+
In city:
(2) +31%2A%28+12+-+a+%29+=+397+-+b+
---------------------------
(2) +372+-+31a+=+397+-+b+
(2) +b+-+31a+=+25+
Substitute (1) into (2)
(2) +36a+-+31a+=+25+
(2) +5a+=+25+
(2) +a+=+5+
+12+-+a+=+7+
and
(1) +b+=+36%2A5+
(1) +b+=+180+
+397+-+b+=+397+-+180+
+397+-+b+=+217+
He drove 180 mi on the highway
he drove 217 mi in the city
-----------------------
check:
(2) +31%2A%28+12+-+a+%29+=+397+-+b+
(2) +31%2A%28+12+-+5+%29+=+397+-+b+
(2) +31%2A7+=+397+-+b+
(2) +b+=+397+-+217+
(2) +b+=+180+
OK


Rational-functions/672676: I am stumped.. when I solved the equation there was no need for the square root method. But that is what my hmwrk question is calling for. Will you please break this problem down for me so that I can see where I am messing up?
(x-3)^2 = 25
1 solutions

Answer 418255 by josmiceli(9664) About Me  on 2012-10-27 20:15:49 (Show Source):
You can put this solution on YOUR website!
+%28+x+-+3+%29%5E2+=+25+
Both sides are a perfect square
So you can take the square root of
both sides to simplify it.
+x+-+3+=+5+
Add 3 to both sides
+x+=+8+
------------
check the answer:
+%28+8+-+3+%29%5E2+=+25+
+5%5E2+=+25+
+25+=+25+
OK


test/672642: An oil tanker can be emptied by a main pump in 4hours an auxiliary pump can empty it in 9 hrs if the main pump is started at 9 am when should the auxiliary pump be started so the tanker will be empty by noon?
1 solutions

Answer 418244 by josmiceli(9664) About Me  on 2012-10-27 18:09:03 (Show Source):
You can put this solution on YOUR website!
From 9 AM to noon is 3 hrs
Let +x+ = number of hours the main pump
is used pumping by itself
+3+-+x+ = number of hours that both pumps are pumping
---------------
The main pump's rate of pumping is ( 1 tanker / 4 hrs )
the auxilliary pump's rate is ( 1 tanker / 9 hrs )
----------------
( fraction of tanker pumped in x hrs ) +
( fraction pumped by both pumps in 3-x hrs ) = 1 whole tanker pumped
+%281%2F4%29%2Ax+%2B+%28+1%2F9+%2B+1%2F4+%29%2A%28+3-x+%29+=+1+
Multiply both sides by +36+
+9x+%2B+%28+4+%2B+9%29%2A%28+3-x+%29+=+36+
+9x+%2B+13%2A%28+3-x+%29+=+36+
+9x+%2B+39+-+13x+=+36+
+-4x+=+-3+
+x+=+.75+
+3+-+x+=+2.25+
The auxiliary pump should be started at 9:45
check answer:
In 3/4 of an hour the main pump empties
+%281%2F4%29%2A%283%2F4%29+=+3%2F16+ of the tanker
In 2.25 hrs, both together empty
+%28+1%2F4+%2B+1%2F9+%29%2A%289%2F4%29+
+%28+9%2F36+%2B+4%2F36+%29%2A81%2F36+
+%28+13%2F36+%29%2A%28+81%2F36+%29+
+%28+13%2A81+%29+%2F+%28+36%5E2+%29+
+1053+%2F+1296+
+13%2F16+
and +13%2F16+%2B+3%2F16+=+1+
OK