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