Thursday
May 5, 2016

Homework Help: math,correction

Posted by Jasmine20 on Wednesday, January 24, 2007 at 3:34pm.

Directions:Multiply

Problem:
((x)/(3)+(3)/(4)) ((3x)/(4)-(3)/(5))

so the answer for it i got:

((20x^2+20x-36)/(80))

I worked it and I have what you have EXCEPT 29x instead of 20x. If you can't find the error, post your work and we can help you find it.

Directions:Multiply

Problem:
((x)/(3)+(3)/(4)) ((3x)/(4)-(3)/(5))

The steps i took:
First i simplify between (x)/(3) and (3)/(4) the common denominator is 12.
Then multiplied: x(4) and 3(3)= ((4x+9)/(12))

between (3x)/(4) and (3)/(5) the common denominator is 20.

so then i multiplied: 3x(5) and 3(4)=
(15x-12)/(20)

Now i have:((4x+9)/(12))((15x-12)/(20))

NOw i multiplied: ((4x+9)(15x)/(240))

now i factored out a 3 out of the top to get:
3((4x+9)(5x-4)/(240))
now i simplify again:
((4x+9)(5x-4)/80)

now foil the top:
f=4x(5x)
o=4x(-4)
i=9(5x)
l=9(-4)

(4x+9)(5x-4)
=4x(5x)+4x(-4)+9(5x)+9(-4)
=20x^2-16x+45x-36
=20x^2+20x-36

NOW i just put that back in:

((4x+9)(5x-4)/(80))

so thats how i came up with:
((20x^2+20x-36)/(80))

((x)/(3)+(3)/(4)) ((3x)/(4)-(3)/(5))

The steps i took:
First i simplify between (x)/(3) and (3)/(4) the common denominator is 12.
Then multiplied: x(4) and 3(3)= ((4x+9)/(12))

between (3x)/(4) and (3)/(5) the common denominator is 20.

so then i multiplied: 3x(5) and 3(4)=
(15x-12)/(20)

Now i have:((4x+9)/(12))((15x-12)/(20))ok to here.

NOw i multiplied: ((4x+9)(15x-12)/(240))
you dropped the -12
now i factored out a 3 out of the top to get:
3((4x+9)(5x-4)/(240))
now i simplify again:
((4x+9)(5x-4)/80)

now foil the top:
f=4x(5x)
o=4x(-4)
i=9(5x)
l=9(-4)

(4x+9)(5x-4)
=4x(5x)+4x(-4)+9(5x)+9(-4)
=20x^2-16x+45x-36
=20x^2+20x-36

OKAY I DON'T SEE IT CAN YOU EXPLAIN TO ME WHAT AM I SUPPOST TO DO.OR WHAT SHOULD IT LOOK LIKE

NOw i multiplied: ((4x+9)(15x-12)/(240))
you dropped the -12.
(4x+9)(15x-12)/240 =
FOIL it.
(60x^2 -48x +135x -108)/240 =
Combine terms.
(60x^2 + 87x -108)/240 =
Divide by 3.
(20x^2 + 29x -36)/80 =

I don't know how your are to leave it in final form but I'm sure you can take it from here.
now i factored out a 3 out of the top to get:
3((4x+9)(5x-4)/(240))
now i simplify again:
((4x+9)(5x-4)/80)

now foil the top:
f=4x(5x)
o=4x(-4)
i=9(5x)
l=9(-4)

(4x+9)(5x-4)
=4x(5x)+4x(-4)+9(5x)+9(-4)
=20x^2-16x+45x-36
=20x^2+20x-36

I appreciate all your help....especially correcting my wrongness.

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