Re: What did you get for Dx[(2x-5)^4] and Dx[x^3] ?(n/t)

Posted by tim on November 11, 2002 at 17:19:08:

In Reply to: What did you get for Dx[(2x-5)^4] and Dx[x^3] ?(n/t) posted by Subhotosh Khan on November 11, 2002 at 07:27:25:

: :
: : : you must use a combination of rules.

: : : start with the product rule (since you are multiplying things), then use power rule.

: : : note that you have x^3(2x-5)^4

: : : so you have a product of x³ and (2x-5)⁴

: : : so D_x[x^3(2x-5)^4]

: : : = x^3*D_x[(2x-5)^4] + (2x-5)^4*D_x[x^3]

: : : where D_x[y] means the derivative of y with respect to x.

: : I can get that far. then im stuck. when i check it on the calculator i get x²(2x-5)^3(14x-15).
: : and i can't get that answer.

for Dx[(2x-5)^4] i get 4(2x-5)^3*2 = 8(2x-5)
for Dx[x^3] i get 3x²

Follow Ups:

• Well then .... Subhotosh Khan 17:44:32 11/11/02 (1)
  • i can't belive i couldn't get that tim 19:15:41 11/11/02 (0)

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