1. ## factor expression

(a2+2a)2-2(a2+2a)-3

u=(a2+2a)

(u)2-2u-3

(u+1)(u-3)

(a2+2a+1)(a2+2a-3)

WORNG ANS (a+1)(a+1)(a-1)(a+3)

2. ## Re: factor expression

I can't see why this is wrong ((a+1)(a+1)(a-1)(a+3))... ...
What is the correct ans?

3. ## Re: factor expression

Originally Posted by zbest1966
WORNG ANS (a+1)(a+1)(a-1)(a+3)
I agree with Goku, this looks correct.

The only other thing you could maybe do is combine the two factors of $\displaystyle a+1$:

$\displaystyle (a+1)(a+1)(a-1)(a+3)$

$\displaystyle =(a+1)^2(a-1)(a+3)$

4. ## Re: factor expression

correct (a+2)(a-2)(a+1)(a-1)

5. ## Re: factor expression

Originally Posted by zbest1966
correct (a+2)(a-2)(a+1)(a-1)
No, that is incorrect. You can verify this by substituting values for $\displaystyle a$.

6. ## Re: factor expression

Originally Posted by zbest1966
(a2+2a)2-2(a2+2a)-3

u=(a2+2a)

(u)2-2u-3

(u+1)(u-3)

(a2+2a+1)(a2+2a-3)
You're on the right track. Now all you need to do is factor those two expresions.

(a2+2a+1) = (a+1)(a+1)
(a2+2a-3) = (a+3)(a-1)