Posted by **Ifi** on Sunday, October 28, 2012 at 4:44am.

Differentiate f(x)= (8-2x)^3(x^2+1)^5.

My ans is 2(8-2x)^2(x^2+1)^4(-3x^2-10x+37). Plz recheck my simplify ans.

-my simplify ans is not the same as wolfram but the long ans is same with wolfram-

- Math -
**Steve**, Sunday, October 28, 2012 at 6:16am
f' = 3(8-2x)^2 (-2) (x^2+1)^5 + 5(8-2x)^3 (x^2+1)^4 (2x)

= (8-2x)^2 (x^2+1)^4 (-6(x^2+1) + 5(8-2x)(2x))

= (8-2x)^2 (x^2+1)^4 (26x^2 - 80x + 6)

= -8(4-x)^2 (x^2+1)^4 (13x^2 - 40x + 3)

which is what Wolfram gets.

Watch for those pesky chain rule factors and minus signs.

- Math -
**Ifi**, Sunday, October 28, 2012 at 8:20am
I still dont get it how do u simplify from

= (8-2x)^2 (x^2+1)^4 (26x^2 - 80x + 6) to

= -8(4-x)^2 (x^2+1)^4 (13x^2 - 40x + 3) ... ?

What can i conclude from it is (4-x)^2 &(13x^2 - 40x + 3) is divided by 2 . Then (x^2+1)^4 is not simplified by any no. Lastly, why do u put -8? if u try to expand it back it didnt get the same ans.

- Math -
**Steve**, Sunday, October 28, 2012 at 11:55am
Really. Forgotten your algebra I?

(8-2x)^2 = 4(4-x)^2

The intervening two lines should have had a "-" sign in front, from the (-2) factor. My typo. No need to pull out the 8; just felt like it. Prolly should leave it as 8-2x, so it looks more like the original syntax.

## Answer this Question

## Related Questions

- Math - Calculate dy/dx, (x^3)(y^7) + 16xy^6=0 My ans is (y(-16-3x^2y))/ x(96+7x^...
- Math - How to d/dx y= (9+((x-9)/6)^1/5)^1/2 ? Hope u can give me the way how to ...
- 6th grade math - Can you check these problems, please? Translate each phrase ...
- Math - Differentiate ln (1+ cos x)... My ans is (-sin x)/ (1+cos x), but at ...
- 7th grade math (probability) - Can you check these, please? Ten cards numbered 1...
- Math - How to differentiate e^e^x? Ans at wolfram is e^(x+e^x). I need the ...
- Math For College Readiness - Simplify the Complex Fractions 1. 8a / 3b^2 / 6ab /...
- chem - an aq. solution(NaCl) made by using 133g diluted to a total solution ...
- math - use implicit differentiation to find dy/dx and then d^2y/dx^2. y^2=ye^x^2...
- 7th grade math - Can you check these? 3. Simplify (56/8+3)*2-1 Ans = (7+3)*2-1...