Q. Find the derivative of the following function.y=log8(−9x5)Answer: y′=
Understand and apply chain rule: Understand the function and apply the chain rule.The function y=log8(−9x5) is a logarithmic function with base 8. To find the derivative, we need to use 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.
Convert base to natural logarithm: Convert the base of the logarithm to the natural logarithm (ln).The derivative of a logarithm with base 8 can be found by converting it to a natural logarithm using the change of base formula: loga(b)=ln(a)ln(b). So, y=log8(−9x5) becomes y=ln(8)ln(−9x5).
Differentiate outer function: Differentiate the outer function.The outer function is ln(−9x5). The derivative of ln(u), where u is a function of x, is u1⋅u′, where u′ is the derivative of u. So, the derivative of ln(−9x5) with respect to x is −9x51 times the derivative of ln(u)0 with respect to x.
Differentiate inner function: Differentiate the inner function.The inner function is −9x5. The derivative of −9x5 with respect to x is −45x4 (using the power rule: dxd[xn]=nxn−1).
Apply chain rule: Apply the chain rule.Now, we multiply the derivative of the outer function by the derivative of the inner function. This gives us ((−9x5)1)×(−45x4).
Simplify expression: Simplify the expression.Simplifying the expression (−9x5)1⋅(−45x4) gives us −−9x545x4 which simplifies to x5.
Include base conversion derivative: Include the derivative of the base conversion.We must not forget to include the denominator ln(8) from the base conversion in Step 2. The final derivative of the function y with respect to x is x5/ln(8).
Write final answer: Write the final answer.The final answer for the derivative of the function y=log8(−9x5) is y′=x5⋅ln(8)1.
More problems from Quotient property of logarithms