# Derivatives with Quotient Law Help

1. Mar 3, 2013

### p.ella

Derivatives with Quotient Law Help!!

I have a test tomorow, any help is much appreciated!! :)

1. The problem statement, all variables and given/known data

Dervive using the quotient rule:

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

My attempt:

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

When I try expanding I get the wrong answer. The final answer's:

[(2-x)^2 (-x-7)] / (x+1)^3

2. Mar 3, 2013

### cepheid

Staff Emeritus
For the red part, you missed a step! You need to use the chain rule on this, so you need to mulitply by the derivative of the "inside" function (which is 2-x). Also, you forgot the part in the denominator for the quotient rule!

3. Mar 3, 2013

### p.ella

Ohhhh that makes so much sense!! Thank you!! :)