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RAY100 answered: 1636 problems
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Answer 144402 by RAY100(1637) on 2009-04-21 13:47:54 (Show Source):
You can put this solution on YOUR website!y=8x^2+4x-1 to form y=a(x-h)^2+k
y=8(x^2+x/2)-1
now must complete square of bracket terms
y=8(x^2 +x/2 +1/16) -1 -8(1/16)
simplify
y=8(x+1/4)^2-1.5
this fits form with
a=(8)
h=(-1/4)
k=(-1.5)
checking
let x=3 solve for y
initial eqn y=8x^2+4x-1= 8(3^2) +4(3)-1=72+12-1=83
final form y=8(x+1/4)^2-1.5=8(3.25)^2-1.5= 8(10.5625)-1.5=84.5-1.5=83 ok
to complete the square we take coefficient of middle term, divide by two, and square it
ie (1/2) , (1/2)/2=1/4, (1/4)^2=(1/16)
this becomes constant term of "square"
since we added this to complete square terms we must subst from constant term to balance eqn. In this case we added 8(1/16) in total therefore we substract (8/16) from constant
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logarithm/192355: log5 square root of 125 - log2 square root of 2= 1 solutions
Answer 144393 by RAY100(1637) on 2009-04-21 13:10:21 (Show Source):
You can put this solution on YOUR website!basic form is log base a of b = ( log b)/(loga)
log base 5 of sq rt 125 - log base 2 of sq rt 2
log of neg number is undefined therefore only use positive sq rts
(log sq rt 125 / log 5 ) -(log sq rt 2/ log 2)
(log 11.18/log5) - (log 1.414/log2)
1.5-.5
1.0
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Rational-functions/192330: 3+(sqroot5x-1)=x 1 solutions
Answer 144389 by RAY100(1637) on 2009-04-21 12:56:54 (Show Source):
You can put this solution on YOUR website!3+sq rt (5x-1) = x
subt 3 each side
sq rt(5x-1) = x-3
sq both sides
+-(5x-1) = (X-3)^2
USING ONLY + answer ( - answer gives imaginary answers)
+(5x-1) = (x-3)(x-3)= x^2-6x+9
subt 5x each side
-1 = x^2 -6x +9 -5x
add 1 to each side
0= X^2 -6x +9 -5x +1
simplifying
0=x^2 -11x +10
factoring
0=(x-10)(x-1)
x=10 and x=1
checking
3 +sq rt (5x-1) = x
3 + sq rt (5(1)-1) = (1)
3 + sqrt 4=1
3+-2 =1 ok with -2
for x=10
3+sqrt (5(10)-1) = (10)
3+ sqrt 49 =10
3+-7=10 ok with +7
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Travel_Word_Problems/192352: A pole that is 2.9 tall casts a shadow that is 1.58 long. At the same time a nearby tower casts a shadow that is 50.5 long. How tall is the tower? Round your answer to the nearest meter. 1 solutions
Answer 144386 by RAY100(1637) on 2009-04-21 12:35:47 (Show Source):
You can put this solution on YOUR website!if a drawing were made showing a line from a point on the ground thru top of tower and then thru top of bldg, we could see two similar triangles. Similar triangles have sides proportional.
in our case h/50.5=2.9/1.58
cross multiplying
1.58 *h=50.5 * 2.9
1.58 *h = 146.45
divide by 1.58
h=92.68987= 92.69
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Numeric_Fractions/192349: What is the angle between the arrows of a clock at 3:15? Record your answer
as precisely as possible. (Hint: The arrows are not at exactly the same place.)
1 solutions
Answer 144384 by RAY100(1637) on 2009-04-21 12:27:38 (Show Source):
You can put this solution on YOUR website!assume the 3:15 is 3 hrs and 15 minutes from zero. AM or PM is not given.
The hr hand has rotated once for every hour plus 90 degrees for 15 minutes or
hr = 360 *3 +90 = 1170 degrees.
the minute hand has rotated 60 times for each hour plus 90 degrees for 15 minutes or
minute hand = 3 *60*360 +90= 64,890 degrees
The difference is 63,720
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Circles/192331: x^2+4x+y^2+6y=2
What is the center and the radius? 1 solutions
Answer 144379 by RAY100(1637) on 2009-04-21 12:10:49 (Show Source):
You can put this solution on YOUR website!basic formula for a circle is
(x-h)^2 + (y-k)^2 = r^2, where h is x center, k is y center, r is radius
to fit this form the given problem must "complete the square"
(x^2 +4x +4) + (y^2 +6y+9) = 2 + (+4)+ (+9)
reviewing take coefficient of the middle term, 4x, divide by 2 and then square, (4/2)^2 =4 and add to both sides of eqn
for y terms, ( 6/2)^2 =9 and add to both sides
Now factor x and y sets
(x+2)^2 + (y+3)^2 = 15
comparing to basic form we find
x center is (-2)
y center is (-3)
rad^2 = 15, rad =sq rt 15 = 3.87
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Numeric_Fractions/192346: Jenny’s trunk has a length of 100 inches, and a width of 20 inches. She
knows from the manufacturer that the volume of her trunk is 20000 cubic
inches. What is the height of the trunk?
1 solutions
Answer 144376 by RAY100(1637) on 2009-04-21 11:52:27 (Show Source):
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Quadratic_Equations/192340: I'm having problems with this type of question
Find the height, of a ball, above ground using the following information.
wait 3 seconds, velocity is 45 ft/sec, initial height above ground is 10 ft
wait 2 seconds, velocity is 95 ft/sec, initial height above ground is 50 ft 1 solutions
Answer 144368 by RAY100(1637) on 2009-04-21 11:19:21 (Show Source):
You can put this solution on YOUR website!This is a physics problem under "projectile motion"
Sometimes it is found in algebra under quadratic topics as a actual application example.
For today, we are asked how high the projectile will go, in a given time, with an initial velocity. The velocity provides the upward energy, and gravity provides the downward energy.
Usually, the angle of the initial velocity is important, but for today we will assume straight up.
If not, let me know.
The basic eqn is:
delta y = v*t - (1/2) (32.2) t^2
where :
delta y is change in height. Note as time progresses, the projectile goes up, reaches a peak, and then comes down.
v is initial velocity. units in this case are ft per sec or ft/sec
t is elapsed time. units are sec
32.2 is gravity. we are using English today. be careful of metric. english units are 32.2 ft per sec squared, or 32.2 ft/sec^2 (metric is 9.8 m/sec^2)
1/2 is a constant to get average acceleration
1st problem
y= vt-1/2 (32.2) t^2
= (45) (3) - 1/2 (32.2) (3^2)
= 135 - 144.9
= (-9.9) ft
Note we started at 10 ft above ground, therefore 10-9.9 = (.1) ft above ground
This is not so nice a first problem. The projectile has been in the air long enough to go fully up, stop, and now decend to just above ground height.
Additional calc shows that the projectile goes up to a peak of about 31.4 ft in 1.4 sec before starting down.
2nd problem
y=vt-16.1t^2 = 95*2 -16.1 * 2^2= 190-64.4=125.6 ft
Again, initial height was 50 ft, therefore final position is 50+125.6 =175.6 ft
additional calc shows peak at about 3 sec of about 140 ft
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Expressions-with-variables/192200: This question is from textbook Algebra 1
Please help, I'm very frustrated and don't understand how to solve linear systems with substitution. I have a lot of homework due tomorrow and don't understand what I'm supposed to do.
x-y=0
12x-5y=-21 1 solutions
Answer 144246 by RAY100(1637) on 2009-04-20 16:47:52 (Show Source):
You can put this solution on YOUR website!1) x-y=0
2) 12x-5y=-21
In substitution we use one eqn to establish a x to y relationship.
Then we substitute this relationship in the other eqn
for example from (1) we know x-y=0, therefore x=y
substituting into (2)
12 (y) -5y = -21
simplify
7y=-21
divide by 7
y=(-3)
substitute this in either (1) or (2) to find x
using (1) x-y=0
x-(-3) =0
y=(-3)
checking
(1) (-3)-(-3)=0 ok
(2) 12(-3) -5(-3) =-21
-36 +15 = -21 ok
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logarithm/192198: Find the solution of the equation, correct to two decimal places: 5Ln(1-x)= 8 1 solutions
Answer 144242 by RAY100(1637) on 2009-04-20 16:37:54 (Show Source):
You can put this solution on YOUR website!5ln(1-x) =8
ln(1-x)^5 =8
e^8=(1-x)^5
2980.958=(1-x)^5
taking 5th root
4.95303 = (1-x)
subt 1 both sides
3.95303 =-x
x=(-3.95303)
checking
5 ln (1-(-3.95303) )=8
5ln 4.95303 =8
5(1.5999) =8
8=8 ok
to 2 dec places x= (-3.95)
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Rational-functions/192035: In the equation 5x/(x+1), what is the end behavior? We are being taught the Ratey method and when I get to the E part of Ratey, i simplify it to 5/1. Does that make it top heavy? If so how do you determine the vertical asymptote? 1 solutions
Answer 144219 by RAY100(1637) on 2009-04-20 15:45:45 (Show Source):
You can put this solution on YOUR website!5x /(x+1)
vertical asymptote at den =0, x+1=0, x=-1
as degrees num and den equal, hor asymptote at 5/1 = +5
sketch vertical line at x=-1, and horizontal line at y=+5
rough sketch shows function starting low at x=-1, rising to rt thru (0,0) to just under asy y=5
starting high at x=-1, function decays to just above hor asy at y=5 as it goes to left
end behavior: as x approaches -infinity, y approaches +5 from +side
as x approaches + infinity, y approaches +5 from - side
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Geometry_Word_Problems/192077: Given (triangle)ABC~(tringle)XYZ, AB=9, BC=18 and AC-21. If the perimeter of (triangle)XYZ is 112, find the measures of the three sides of (triangle)XYZ. 1 solutions
Answer 144216 by RAY100(1637) on 2009-04-20 15:29:57 (Show Source):
You can put this solution on YOUR website!Draw a rough sketch of two similar triangles
label sides carefully
as triangles are similar, sides are proportional
per of given triangle abc = 9 + 18 + 21 = 48.
per of new triangle is 112
as perimeters vary as scale factor to 1st power
sf = 112/48 =2 1/3 =7/3
xy = (7/3)ab =7/3 * 9 = 21
yz = (7/3) bc = 7/3*18 = 42
xz = (7/3) ac = 7/3*21 = 49
checking per 2nd triangle = 21+42+49= 112 ok
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Equations/192180: I am having issues figuring out the inverse variation. Here is the problem
Suppose z varies inversely with t and that z=12 and t=10. What is the value of z when t = 6 1 solutions
Answer 144213 by RAY100(1637) on 2009-04-20 15:19:02 (Show Source):
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Linear-systems/192176: Could you help me with the following problem?
Solve the system algebraically.
5x+2y=10
3x+2y=6
Make sure there are no spaces in your answer. Be sure to include a comma.
Answer{( )} 1 solutions
Answer 144209 by RAY100(1637) on 2009-04-20 15:15:11 (Show Source):
You can put this solution on YOUR website!1) 5x +2y = 10
2) 3x +2y =6
subt (1) - (2)
2x =4
divide by 2
x=2
subst in (1)
5(2) +2y =10
10 +2y =10
subt 10 both sides
2y =0
y=0
answer (2,0)
checking
1) 5(2) +2(0) =10 ok
2) 3(2) = 2(0) =6 ok
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Polynomials-and-rational-expressions/192169: Can you please help me solve this problem?
5/2x+1/4x=7/4+x
Thank you so much; I really appreciate your help! 1 solutions
Answer 144203 by RAY100(1637) on 2009-04-20 14:58:43 (Show Source):
You can put this solution on YOUR website!(5/2)x +(1/4)x =(7/4) +x
Multiply by 4
10x +x=7+4x
7x=7
x=1
check
5/2 +1/4 =7/4 +1
10/4 +1/4 =7/4 +4/4
11/4 = 11/4 ok
if you really did mean
5/(2x) +1/(4x) =7/4 +x
mult by 4x
10 +1 = 7x +4x^2
0= 4x^2 -7x -11
0= (4x+11) (x-1)
x=(1) and x=(-11/4)
checking x=1
5/2 +1/4 =7/4 +1 ok
checking x=( -11/4)
5/-22/4 +1/-44/4 = 7/4 -11/4
-20/22 -2/22 = -4/4
-22/22 =-4/4 ok
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Equations/192161: I home school and I am stuck on a problem.
all the information the directions give me is "solve each equation"
The worksheet is on radical equations' graphs, and complex numbers
Please help me solve this equation:
(2x-3)^2=-24 1 solutions
Answer 144197 by RAY100(1637) on 2009-04-20 14:25:56 (Show Source):
You can put this solution on YOUR website!(2x-3)^2=24
take sq rt of both sides
2x-3 = sq rt 24 = +- (4.899)
2x-3 =+4.899
2x = 7.899
x= 3.95
or 2x-3= -4.899
2x = -1.899
x=-.95
checking
(2(3.95) -3 )^2= 24 ok
( 2(-.95) -3)^2 =24 ok
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Proportions/192130: This question is from textbook
For the following problem you need to give a proportion whose solution gives the answer to the problem. You must name the variable that you used in the proportion.
A lawyer bills her clients $300 per hour of service. If a client's case requires 17 hours to complete, use a proportion to calculate how much the client will owe the lawyer (excluding tax)
Thank You to all! 1 solutions
Answer 144195 by RAY100(1637) on 2009-04-20 14:09:44 (Show Source):
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Rational-functions/192141: For each rational function, identify any holes or horizontal or vertical asymptotes of its graph.
y= -2(x-8)/(8-x)
I have tried a couple different things, but I am not sure if any of them are correct.
First attempt:
There would be a vertical asymptote at x=8.
There would be a horizontal asymptote at y=-2.
Second attempt:
There would be a hole at (8,2)
Third attempt:
There would vertical asymptote at x=8.
There would be a horizontal asymptote at y=2.
I am extremely confused any help would be greatly appreciated! 1 solutions
Answer 144190 by RAY100(1637) on 2009-04-20 13:53:28 (Show Source):
You can put this solution on YOUR website!good work
an easier approach might be
y=-2(x-8)/(8-x)
simplify to
y= 2(x-8) / (x-8)
cancelling (x-8) 's gives us y=+2 but with a hole at x=8
no vertical asymptotes ( ie den =0)
no real horizontal asymptotes except y does always =2
review of horiz asymptotes, y = a(n)x^n +..... / b(m) x^m +.....
if n less than m, hor asy at y=0
if n=m, hor asy at y=a(n)/b(m)
and if n>m, no hor asy
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Problems-with-consecutive-odd-even-integers/192149: find two consecutive odd integers such that the square of the larger is 3 than 12 times the smaller
x, x+2 1 solutions
Answer 144186 by RAY100(1637) on 2009-04-20 13:35:14 (Show Source):
You can put this solution on YOUR website!let smaller +x
let larger = x+2
The problem only makes sense if " is three than" reads " is 3 smaller than"
to solve this problem
l^2 = 12 S-3
(x+2)^2 =12(x) -3
x^2 +4x+4 =12x -3
subt 12 x both sides
x^2 +4x -12x +4 =-3
now add 3 to both sides
x^2 +4x -12x +4 +3 =0
x^2 -8x +7 =0
factoring
(x-7) (x-1) =0
setting both =0
x-7=0, x=7 (smaller) & larger =9
or x-1=0, x=1 (smaller) & larger is 3
checking (l^2=12*s-3)
3^2=12(1)-3 ok
9^2 = 12(7)-3 or 81=84-3 ok
Therefore both sets are correct, 1 &3, and 7&9
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Polynomials-and-rational-expressions/192140: This question is from textbook saxon algebra 2
Identify the leading coefficient and degree, and describe the end behavior of f(x)=2x^5+4x^4-x
leading coefficient=2+
degree=5odd
describe the end behavior? 1 solutions
Answer 144184 by RAY100(1637) on 2009-04-20 13:19:20 (Show Source):
You can put this solution on YOUR website!GOOD JOB
END BEHAVIOR is fancy for what happens to function for very big or small numbers
for the ODD functions they in general slant up for positive leading coefficients
or slant down for negative leading coefficients.
This is a positive therefore it will slant up
the end on the left side will be y approaches (-infinity) as x approaches (- infinity)
the end on the right side wiil be y approaches (+ infinity) as x approaches ( + infinity)
as it is 5th degree it should have 4 turns as it goes from lower left to upper right on graph
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Numeric_Fractions/192134: -6 +[-11 +5] / 4^2 -(-9)
i think my text book is wrong because they got 0 as an answer
is 0 the correct answer 1 solutions
Answer 144182 by RAY100(1637) on 2009-04-20 12:56:04 (Show Source):
You can put this solution on YOUR website!review original problem please
IF ( (-6) +(11-5) ) / 4^2 - (-9) or thereabouts
numerator will be zero and problem will be zero
STATED PROBLEM
(-6) + (-11+5)/4^2 -(-9)
-6+ (-6)/16 +9
3 -(3/8)
2 5/8
2.625
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Functions/192136: Find the domain of the function
f(x)=
5x-1
-----
x^2-16 1 solutions
Answer 144181 by RAY100(1637) on 2009-04-20 12:44:02 (Show Source):
You can put this solution on YOUR website!f(x) =y=(5x-1)/(x^2-16)
Normally in Domain problems we seek when denominator =0
this becomes easier to see if we factor denominator
y= (5x-1) / ( x+4) (x-4)
x+4 =0, x=-4
x-4 =0, x=4
Therefore domain is all Real numbers except x= +4, or =-4
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Average/192120: If f(x) = (5x-3)/(x-2)
Find the inverse function of f. would that be just the opposite? = (x-2)/(5x-3)?
State the domain of f. State the domain of the inverse function. 1 solutions
Answer 144173 by RAY100(1637) on 2009-04-20 11:36:37 (Show Source):
You can put this solution on YOUR website!INVERSE of a number is reciprocal, ie 2, inv 2 = 1/2
however inverse of FUNCTION indicates a function that is reflected over y=x
Normally this is solved by substituting x for y ,,,, and y for x
f(x) =(5x-3) / (x-2)
but f(x) =y
y = (5x-3) / (x-2) DOMAIN is all REAL numbers except x=2
inverting
x = (5y-3) / (y-2)
or (y-2) = (5y-3) /x Domain is all REAL numbers except x=0
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