Q. Given the function f(x)=−5(5x2+6x−8)5, find f′(x) in any form.Answer: f′(x)=
Identify Functions: To find the derivative of the function f(x)=−5(5x2+6x−8)5, we will use the chain rule. The chain rule states that the derivative of a composite function is the derivative of the outer function evaluated at the inner function times the derivative of the inner function.
Find Outer Function Derivative: First, let's identify the outer function and the inner function. The outer function is g(u)=−5u5 and the inner function is u(x)=5x2+6x−8. We will find the derivative of each function separately.
Find Inner Function Derivative: The derivative of the outer function g(u)=−5u5 with respect to u is g′(u)=−5×5u5−1=−25u4.
Apply Chain Rule: The derivative of the inner function u(x)=5x2+6x−8 with respect to x is u′(x)=2⋅5x+6=10x+6.
Substitute Derivatives: Now, we apply the chain rule: f′(x)=g′(u(x))⋅u′(x). Substituting the derivatives we found, we get f′(x)=(−25u4)⋅(10x+6).
Replace Inner Function: We need to replace u with the inner function u(x)=5x2+6x−8 to express the derivative entirely in terms of x. So, f′(x)=−25(5x2+6x−8)4⋅(10x+6).
Simplify Expression: Finally, we simplify the expression by distributing the −25: f′(x)=−25×(10x+6)×(5x2+6x−8)4.
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