1. ## Differentiation Help

I've been working on this problem and can't figure out how to get to the right answer.

The problem:
(5x-2)^2(2-x^4)^4

I got:
2(5x-2)(2-x^4)^3(20+16x^3-50x^4)
But the correct answer, according to the online set, is:
2(5x-2)(2-x^4)^3(10+16x^3-45x^4)

I sometimes get tripped up on factoring out, but I can't see where I went wrong. My answer seems right. I don't know how to get to the correct answer.

2. ## Re: Differentiation Help

Originally Posted by crumiecake
I've been working on this problem and can't figure out how to get to the right answer.

The problem:
(5x-2)^2(2-x^4)^4

I got:
2(5x-2)(2-x^4)^3(20+16x^3-50x^4)
But the correct answer, according to the online set, is:
2(5x-2)(2-x^4)^3(10+16x^3-45x^4)

I sometimes get tripped up on factoring out, but I can't see where I went wrong. My answer seems right. I don't know how to get to the correct answer.
next time, show your steps so that one may possibly locate your error ...

$(5x-2)^2 \cdot 4(2-x^4)^3 \cdot (-4x^3) + (2-x^4)^4 \cdot 2(5x-2) \cdot 5$

$2(5x-2)(2-x^4)^3 [(5x-2)(-8x^3) + 5(2-x^4)]$

$2(5x-2)(2-x^4)^3 [-40x^4 + 16x^3 + 10 - 5x^4]$

$2(5x-2)(2-x^4)^3 (-45x^4 + 16x^3 + 10)$