Math Q

[Mstoothlady2012]

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Can some1 solve this for me plzz, I am getting the answer which is not even one of the answer choices.

1/2[(3x-1)^2 - (3x + 1)^ 2]

a) -12x-1
b) 6x +1
c) 6x
d) -6x
e) 12x

Thanks!

 

[Orgodox]

I got D Ill show try and show my work is that right?

 

[Orgodox]

First get the inside of the parenthesize:

(3x-1)^2 = (3x-1)(3x-1)= 9x^2 -6x+1
(3X+1)^2 = (3X+1)(3X+1)= 9x^2 + 6+1

If you subtract t hem the 9x^2 cancels and so do the ones and your left with
1/2(-12x)= -6x

 

[Thundercatz]

Is the answer -6x?

1/2 [(9x2 - 6x +1) - (9x2 + 6x + 1)] = 1/2 [9x2 -6x +1 - 9x2 - 6x - 1] =

1/2[-12x] = -6x

 

[Mstoothlady2012]

First get the inside of the parenthesize:

(3x-1)^2 = (3x-1)(3x-1)= 9x^2 -6x+1
(3X+1)^2 = (3X+1)(3X+1)= 9x^2 + 6+1

If you subtract t hem the 9x^2 cancels and so do the ones and your left with
1/2(-12x)= -6x

shoot! I was doing this wrong. I kept on solving it has 9x^2 - 6x - 1 lol Thanks!

 

[Streetwolf]

Can some1 solve this for me plzz, I am getting the answer which is not even one of the answer choices.

1/2[(3x-1)^2 - (3x + 1)^ 2]

a) -12x-1
b) 6x +1
c) 6x
d) -6x
e) 12x

Thanks!

Easier way is to use a^2 - b^2 = (a+b)(a-b)

Here we have a^2 = (3x-1)^2 and b^2 = (3x+1)^2

You get 1/2 * [(3x - 1) + (3x + 1)] * [(3x - 1) - (3x + 1)]

Equals (1/2) * (6x) * (-2) = -6x