# Find the derivative of the function

1. Jan 25, 2012

### bobsmith76

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

3. The attempt at a solution

I don't understand how in the final step they got the numerator. Where's the 45 come from? what happened to 2t+1?, or in the denominator they got (2t+1) raised to the 10th power.

Last edited: Jan 25, 2012
2. Jan 25, 2012

### Dick

h'(x)=2. Why do you say '2 or 1'?? And (2t+1)*1-2*(t-2)=5. Multiply it out. Finally $({\frac{t-2}{2t+1})}^8=\frac{(t-2)^8}{(2t+1)^8}$. Does that help?

Last edited: Jan 25, 2012
3. Jan 25, 2012

### bobsmith76

You read my post before I edited it. I'm still having trouble getting 45, and the 10th power in the denominator.

4. Jan 25, 2012

### Dick

9*5=45. And (2t+1)^8*(2t+1)^2=(2t+1)^10.

5. Jan 25, 2012

### bobsmith76

Ok, I figured out the numerator, I can get 45 now. But I still can't get the 10th power in the denominator.

6. Jan 25, 2012

### SithsNGiggles

9 ((t - 2)/(2t + 1))^8 ((2t + 1)(1) - (2)(t -2))/(2t + 1)^2)

9 ((t - 2)/(2t + 1))^8 (2t + 1 - 2t + 4)/(2t + 1)^2

Simplify from here.

Also, ((t - 2)/(2t + 1))^8 is the same as (t - 2)^8/(2t + 1)^8

7. Jan 25, 2012

### bobsmith76

Thanks, I got it now.