Q. Find the derivative of the following function.y=73x5−2x4Answer: y′=
Identify Function Components: Identify the function and its components.We have y=73x5−2x4. This is an exponential function with base 7 and an exponent that is a polynomial in x.
Apply Chain Rule: Apply the chain rule for derivatives.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. In this case, the outer function is 7u and the inner function is u(x)=3x5−2x4.
Differentiate Outer Function: Differentiate the outer function with respect to the inner function.The derivative of au with respect to u is au⋅ln(a), where a is a constant and u is a function of x. Therefore, the derivative of 7u with respect to u is 7u⋅ln(7).
Differentiate Inner Function: Differentiate the inner function with respect to x. The inner function u(x)=3x5−2x4 is a polynomial, and we can differentiate it term by term. The derivative of 3x5 with respect to x is 15x4, and the derivative of −2x4 with respect to x is −8x3. Therefore, the derivative of u(x) is 15x4−8x3.
Combine Using Chain Rule: Combine the results using the chain rule.The derivative of y with respect to x is the derivative of the outer function evaluated at the inner function times the derivative of the inner function. This gives us y′=(73x5−2x4⋅ln(7))⋅(15x4−8x3).
Simplify Expression: Simplify the expression.We can leave the derivative in its factored form, as y′=(73x5−2x4⋅ln(7))⋅(15x4−8x3), or we can distribute the ln(7) to both terms in the parentheses, but it is not necessary for the final answer.
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