Q. Given the function f(x)=4(−x2−9x+3)5, find f′(x) in any form.
Identify Functions: We need to find the derivative of the function f(x)=4(−x2−9x+3)5. This requires the use of the chain rule, which 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 Derivatives: First, let's identify the outer function and the inner function. The outer function is g(u)=4u5 and the inner function is u(x)=−x2−9x+3. We will need to find g′(u) and u′(x).
Apply Chain Rule: The derivative of the outer function g(u)=4u5 with respect to u is g′(u)=20u4.
Simplify Expression: The derivative of the inner function u(x)=−x2−9x+3 with respect to x is u′(x)=−2x−9.
Final Derivative: Now we apply the chain rule. The derivative of f(x) with respect to x is f′(x)=g′(u(x))⋅u′(x). Substituting the derivatives we found, we get f′(x)=20(−x2−9x+3)4⋅(−2x−9).
Final Derivative: Now we apply the chain rule. The derivative of f(x) with respect to x is f′(x)=g′(u(x))⋅u′(x). Substituting the derivatives we found, we get f′(x)=20(−x2−9x+3)4⋅(−2x−9).Simplify the expression for f′(x) by distributing the 20 into the term (−2x−9). This gives us f′(x)=20⋅(−2x−9)⋅(−x2−9x+3)4.
Final Derivative: Now we apply the chain rule. The derivative of f(x) with respect to x is f′(x)=g′(u(x))⋅u′(x). Substituting the derivatives we found, we get f′(x)=20(−x2−9x+3)4⋅(−2x−9).Simplify the expression for f′(x) by distributing the 20 into the term (−2x−9). This gives us f′(x)=20⋅(−2x−9)⋅(−x2−9x+3)4.The final form of the derivative is f′(x)=−40x(−x2−9x+3)4−180(−x2−9x+3)4. This is the derivative of the function f(x) in any form.
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