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expressions/495047: my math teacher gave us a question like this.....find out if the statement is always,sometimes,or never true.here is the statement
-(positive)(positive)(-negative)=negative
me and my dad dont get why there is a - before the problem because on the next question one of the paranthesis says it without a - but the other one does.My paper is due monday and i need to understand the question so please reply fast!!
_______________________________________________________________________________
1 solutions

Answer 335910 by Alan3354(31518) About Me  on 2011-09-10 17:40:06 (Show Source):
You can put this solution on YOUR website!
-(positive)(positive)(-negative)=negative
------------
You can cancel the positives, they have no effect on the sign.
------
-(-negative)=negative
The 2 minus signs --> a positive
negative=negative
Always true.
--------------
The next question has nothing to do with this question.


Complex_Numbers/495037: x^4= 16
using complex numbers solve for x. couldn't find any examples like this in the book.
i get the same answer every time : 2, -2 yet the back of the book has -2i and 2i also.
1 solutions

Answer 335905 by Alan3354(31518) About Me  on 2011-09-10 17:21:02 (Show Source):
You can put this solution on YOUR website!
x%5E4+=+16
x%5E4+-+16+=+0
%28x%5E2-4%29%2A%28x%5E2%2B4%29+=+0
x%5E2-4+=+0
x = -2, +2
----------
x%5E2%2B4+=+0
x%5E2+=+-4
x = -2i, +2i
--------------
The number of roots = the order of the equation.
4th order --> 4 roots
Sometimes the roots are repeated, eg, x^3=0
--> x = 0,0,0
3 roots, of 0, multiplicity 3


Complex_Numbers/494983: how would you find x and y
x-y=6
2x/3+y/3=1
1 solutions

Answer 335884 by Alan3354(31518) About Me  on 2011-09-10 15:59:12 (Show Source):
You can put this solution on YOUR website!
I would multiply the 2nd eqn by 3 and add them.


Travel_Word_Problems/494942: You are driving in Canada. The sign says that you are 80 km from Ottawa. You are traveling at 75 mph. How long will it take you to reach Ottawa?
1 solutions

Answer 335869 by Alan3354(31518) About Me  on 2011-09-10 14:15:55 (Show Source):
You can put this solution on YOUR website!
1 mile =~ 1.609 km
75 mi/hr = 75*1.609 km/hr
t = 80/(75*1.609) =~ 0.6629 hours


Problems-with-consecutive-odd-even-integers/494874: find three consecutive whole numbers that total 75.
I know the answer is 24,25 and 26, but I do not know how to write the equation.
would it be a+a+1+a+2=75
3a+3=75
3a=72
a=24




i
1 solutions

Answer 335865 by Alan3354(31518) About Me  on 2011-09-10 13:54:24 (Show Source):
You can put this solution on YOUR website!
find three consecutive whole numbers that total 75.
I know the answer is 24,25 and 26, but I do not know how to write the equation.
would it be a+a+1+a+2=75
3a+3=75
3a=72
a=24
-----------
would it be a+a+1+a+2=75
Yes, it would.


Unit_Conversion_Word_Problems/494912:
How do I convert 36 cubic cm/sec to mph? I need to know the steps.
Thanks
1 solutions

Answer 335864 by Alan3354(31518) About Me  on 2011-09-10 13:45:45 (Show Source):
You can put this solution on YOUR website!
Cubic cm is volume. Volume/sec doesn't convert to speed.


Quadratic_Equations/494920: a rock falls from a tower that is 320 feet high. As it is falling, its height is given by the formula h=320-16t^2. How many seconds (in tenths) will it take to get to the ground.(h=0)?
My solution
0=-16t^2+320t
0=-4t(4t-80)
4t=0 or 4t-80=0
t=0 or t=20
0 doesn't answer the question so I get 20 seconds. The answer key on my study sheet says 4.5 seconds. I am not sure what I did wrong. Thanks!
1 solutions

Answer 335863 by Alan3354(31518) About Me  on 2011-09-10 13:44:03 (Show Source):
You can put this solution on YOUR website!
a rock falls from a tower that is 320 feet high. As it is falling, its height is given by the formula h=320-16t^2. How many seconds (in tenths) will it take to get to the ground.(h=0)?
My solution
0=-16t^2+320t
0=-4t(4t-80)
4t=0 or 4t-80=0
t=0 or t=20
0 doesn't answer the question so I get 20 seconds. The answer key on my study sheet says 4.5 seconds.
--------------
0=-16t^2+320 Not 320 t
-----------
16t^2 = 320
t^2 = 20
t = sqrt(20) =~ 4.472 seconds


Points-lines-and-rays/494860: 1)The rotor blades of an helicopter are 16ft long and are rotaing at 120rmp.
a)Find the angular speed of the rotor.
b)find the linear speed of a point on the tip of a blade .

2)Find the perimeter of a regular hexagon that is inscribed in a circle of radius 8m.
1 solutions

Answer 335833 by Alan3354(31518) About Me  on 2011-09-10 10:24:52 (Show Source):
You can put this solution on YOUR website!
1)The rotor blades of an helicopter are 16ft long and are rotaing at 120rmp.
a)Find the angular speed of the rotor.
120 rev/min = 120*2*pi radians/min
= 240pi rad/min
------------
b)find the linear speed of a point on the tip of a blade
The circumference = 16*2*pi feet
Tip speed = 16*2*pi*120 ft/min
= 3840pi ft/min
----------------
That helicopter is not likely to fly at those blade speeds, way too slow.
----------------
2)Find the perimeter of a regular hexagon that is inscribed in a circle of radius 8m.
The central angles are 60 degs, making 6 equilateral triangles with sides of 8 m.
Perimeter = 6*8 = 48 m


expressions/494728: 5x squared = 270 I keep getting -6 square root 3, 6 square root3. But that's not right
1 solutions

Answer 335763 by Alan3354(31518) About Me  on 2011-09-09 21:56:34 (Show Source):
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5x%5E2+=+270
x%5E2+=+54+=+9%2A6
x = +/- 3sqrt(6)


Linear-equations/494730: Find f(4) when f(x) = 2n - 1
1 solutions

Answer 335762 by Alan3354(31518) About Me  on 2011-09-09 21:55:10 (Show Source):
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Is it x or n?


Numeric_Fractions/494699: can you please explain to me how you got (3/4)+(1/5)=19/20?
1 solutions

Answer 335761 by Alan3354(31518) About Me  on 2011-09-09 21:54:34 (Show Source):
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3/4 = 15/20
1/5 = 4/20


Travel_Word_Problems/494719: How long does a 30 minute flight take going 600mph.


1 solutions

Answer 335760 by Alan3354(31518) About Me  on 2011-09-09 21:53:45 (Show Source):


Subset/494526: Find all subsets of D= {a,b,c,d}
1 solutions

Answer 335713 by Alan3354(31518) About Me  on 2011-09-09 16:02:13 (Show Source):
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There are 4 elements.
Subsets = 2^4 = 16


Linear-systems/494596: Solve the following systems of equations using a method of your choice.
6x-y=-4
2x=2y=15
1 solutions

Answer 335712 by Alan3354(31518) About Me  on 2011-09-09 16:01:06 (Show Source):
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2x=2y=15 too many equal signs.


Polygons/494528: What is the sum of the interior angles of a regular polygon with 53 sides
1 solutions

Answer 335711 by Alan3354(31518) About Me  on 2011-09-09 15:58:46 (Show Source):
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The sum of the interior angles of a polygon (regular or not) is
(n-2)*180
= 51*180 degs


Surface-area/494546: A 2 ft. cube has how many square feet of surface area?

1 solutions

Answer 335710 by Alan3354(31518) About Me  on 2011-09-09 15:55:53 (Show Source):
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Find the area of a side.
There are 6 sides.


Functions/494597: what is the answer to the problem f(m)=6m+7?
1 solutions

Answer 335709 by Alan3354(31518) About Me  on 2011-09-09 15:55:03 (Show Source):
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Is that a function?
What is the problem?
A function
f(m) = 6m+7 is not a problem.


percentage/494561: convert the decimal to a fraction. be sure to show all of your work.
0.55
1 solutions

Answer 335708 by Alan3354(31518) About Me  on 2011-09-09 15:53:24 (Show Source):
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0.55 = 0.55/1
= 55/100
= 11/20


Square-cubic-other-roots/494572: What is the square root of sqrt 729 + sqrt 900 =
1 solutions

Answer 335706 by Alan3354(31518) About Me  on 2011-09-09 15:52:25 (Show Source):
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Find the square root of each number and add them.


Square-cubic-other-roots/494573: What is the Square root of ^64 + ^10
1 solutions

Answer 335705 by Alan3354(31518) About Me  on 2011-09-09 15:51:43 (Show Source):
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What does ^ mean?


Volume/494590: the volume of a cube depends on the length of its side. a cube with a side length of 10 feet has a volume of 1000 cubic feet. a cubic with a side length of 2 feet has a volume of 8 cubic feet.
1 solutions

Answer 335699 by Alan3354(31518) About Me  on 2011-09-09 15:34:25 (Show Source):


Average/494507: I am taking a test and it has 28 questions I missed 5 of them, what is the percentage of that. I need 90% to pass.
1 solutions

Answer 335673 by Alan3354(31518) About Me  on 2011-09-09 12:30:41 (Show Source):
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23 of 28 were correct
23/28 =~ 0.82
= 82%
-----------
Is this one that you missed?


Miscellaneous_Word_Problems/494485: After taking 7 quizzes, your average is 72 of 100. What must your average be on the next five quizzes to increase your average to 77?
1 solutions

Answer 335672 by Alan3354(31518) About Me  on 2011-09-09 12:28:06 (Show Source):
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After taking 7 quizzes, your average is 72 of 100. What must your average be on the next five quizzes to increase your average to 77?
---------------
7*72 = 504
12*77 = 924
You need 420 points on the next 5.
420/5 = 84 average for the 5


Finance/494504: Hello,
It's a general maths question.
For example if I have: x=2(b-a)/(b-a)
and I allowed to cross out the 2 brackets (b-a) and simply state that x=2
or are there some steps in order to conclude to that answer?
Thank you!
(P.S.sorry for not selecting the apt topic, but the box wasn't working!)
1 solutions

Answer 335671 by Alan3354(31518) About Me  on 2011-09-09 12:24:14 (Show Source):
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Hello,
It's a general maths question.
For example if I have: x=2(b-a)/(b-a)
and I allowed to cross out the 2 brackets (b-a) and simply state that x=2
or are there some steps in order to conclude to that answer?
--------------
You can cancel the b-a terms, but you have the restriction that
b-a cannot equal zero, --> b not equal to a.
The denominator cannot be zero.


test/494501: What is the answer to:
4x7g
1 solutions

Answer 335670 by Alan3354(31518) About Me  on 2011-09-09 12:11:45 (Show Source):
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If you mean multiply, it's 28g
------------
Use the asterisk for multiply, 4*7g
x is often used as a variable.


Money_Word_Problems/494471: How long does it take to double an investment of $1,000 in an amount that pays 8% annual interest rate if:
1. Interest is compounded quarterly?
2. Interest is compounded continuously?
1 solutions

Answer 335669 by Alan3354(31518) About Me  on 2011-09-09 12:03:55 (Show Source):
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How long does it take to double an investment of $1,000 in an amount that pays 8% annual interest rate if:
1. Interest is compounded quarterly?
8% annual = 2% per quarter
FV = PV*(1 + 0.02)^n
2 = (1.02)^n the amount is irrelevant, any amount will be doubled.
log(2) = n*log(1.02)
n = log(2)/log(1.02)
n =~ 35.003 quarters
You can use logs or ln, natural logs, same result
----------------------
2. Interest is compounded continuously?
FV = PV*e^rt = PV*e^0.08t
2 = e^0.08t
ln(2) = 0.08t
t = ln(2)/0.08
t =~ 8.66434 years
= 34.66 quarters
Not much difference


Graphs/494479: x+y=6
3x-4y=4
1 solutions

Answer 335668 by Alan3354(31518) About Me  on 2011-09-09 11:56:03 (Show Source):
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Multiply the 1st eqn by 4, then add.


Linear-equations/494481: Solve for the given variable if the line through the two given points is to have the given slope. (3,2) and (4,j), m=1
Please show work so I understand how you got the answer. Thanks so much.
1 solutions

Answer 335667 by Alan3354(31518) About Me  on 2011-09-09 11:55:12 (Show Source):
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Solve for the given variable if the line through the two given points is to have the given slope. (3,2) and (4,j), m=1
-----------------
Slope m = diffy/diffx
m = (2-j)/(3-4) = (2-j)/-1 = j-2
j-2 = 1
j = 3


Graphs/494496: Is there a benefit to doing graphing?

1 solutions

Answer 335666 by Alan3354(31518) About Me  on 2011-09-09 11:53:02 (Show Source):
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Sometimes, not always


Polygons/494493: The sum of interior angles of a regular polygon is 2880.
a) calculate the size of each exterior angle of the polygon.
b) calculate the size of each angle at the centre of the polygon.
1 solutions

Answer 335665 by Alan3354(31518) About Me  on 2011-09-09 11:52:14 (Show Source):
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Sum of interior angles = (n-2)*180
Solve for n
-----------
Each interior angle = 2880/n
Each angle at the center = 360/n


Geometric_formulas/494492: whats the anwser to 15-24divided by4times 2
1 solutions

Answer 335664 by Alan3354(31518) About Me  on 2011-09-09 11:49:43 (Show Source):
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It depends.
Is it 15+-+24%2F%284%2A2%29 ?
Or %28%2815-24%29%2F4%29%2A2 ?
Or something else?
You have to clarify it. Use numbers and symbols, / for divide, * for multiply, and parentheses.