Q. Find the derivative of g(x)=3cos−1(x) at the point x=41.
Identify function: Identify the function to differentiate.We are given the function g(x)=3cos−1(x), which is 3 times the inverse cosine of x. We need to find its derivative with respect to x.
Apply chain rule: Apply the chain rule for differentiation.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. The outer function here is 3 times a function, and the inner function is cos−1(x).
Differentiate outer function: Differentiate the outer function.The derivative of 3 times a function is simply 3 times the derivative of that function. So we will need to multiply the derivative of cos−1(x) by 3.
Differentiate inner function: Differentiate the inner function.The derivative of cos−1(x) with respect to x is −1−x21. This comes from the standard derivative formulas for inverse trigonometric functions.
Combine derivatives: Combine the derivatives using the chain rule. Multiplying the derivative of the outer function by the derivative of the inner function, we get g′(x)=3×(−1−x21).
Simplify derivative: Simplify the derivative.Simplifying the expression, we have g′(x)=−1−x23.
Evaluate at x=41: Evaluate the derivative at the given point x=41. Plugging x=41 into the derivative, we get g′(41)=−1−(41)23.
Calculate value: Calculate the value of the derivative at x=41. Calculating the value, we have g′(41)=−1−1613=−16153=−15341.
Simplify final expression: Simplify the final expression.Simplifying the expression, we get g′(41)=−415/43=−153.
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