Find all points c satisfying the conclusion of the MVT for the function f(x)=9xln(x)+9 and interval [1,9]. (Use decimal notation. Give your answer to three decimal places. Give your answer as comma-separated list.)
Q. Find all points c satisfying the conclusion of the MVT for the function f(x)=9xln(x)+9 and interval [1,9]. (Use decimal notation. Give your answer to three decimal places. Give your answer as comma-separated list.)
Mean Value Theorem: The Mean Value Theorem states that if a function f is continuous on the closed interval [a,b] and differentiable on the open interval (a,b), then there exists at least one number c in (a,b) such that f′(c)=b−af(b)−f(a). We need to find the derivative of f(x), which is f′(x).
Calculate Derivative: Calculate the derivative of f(x)=9xln(x)+9 using the product rule and the chain rule. The derivative of ln(x) is x1, and the derivative of x is 1. So, f′(x)=9ln(x)+9⋅(x1)⋅x=9ln(x)+9.
Evaluate Function Values: Evaluate f(1) and f(9) to find the average rate of change over the interval [1,9]. Since ln(1)=0, f(1)=9×1×0+9=9. To find f(9), we calculate 9×9×ln(9)+9.
Calculate Average Rate: Calculate f(9)=9×9×ln(9)+9. We know that ln(9) is approximately 2.197 (using a calculator), so f(9)≈9×9×2.197+9=178.761+9=187.761.
Set Derivative Equal: Now, calculate the average rate of change (f(b)−f(a))/(b−a) using f(1)=9 and f(9)≈187.761. The average rate of change is (187.761−9)/(9−1)=178.761/8=22.345125.
Isolate Natural Logarithm: Set the derivative f′(c) equal to the average rate of change to find c. So, we have 9ln(c)+9=22.345125. We need to solve this equation for c.
Solve for ln(c): Subtract 9 from both sides of the equation to isolate the natural logarithm term: 9ln(c)=22.345125−9. This simplifies to 9ln(c)=13.345125.
Exponentiate to Find c: Divide both sides of the equation by 9 to solve for ln(c): ln(c)=913.345125. This simplifies to ln(c)≈1.482791667.
Calculate Approximate Value: Exponentiate both sides to solve for c: eln(c)=e1.482791667. This simplifies to c≈e1.482791667.
Calculate Approximate Value: Exponentiate both sides to solve for c: eln(c)=e1.482791667. This simplifies to c≈e1.482791667.Use a calculator to find the value of c: c≈e1.482791667≈4.405.