Q. For the function f(x)=9x2−8x−7, find the slope of the tangent line at x=9.Answer:
Calculate Derivative: To find the slope of the tangent line at a specific point, we need to calculate the derivative of the function, which gives us the slope of the tangent line at any point x.
Evaluate at x=9: The derivative of f(x)=9x2−8x−7 with respect to x is f′(x)=18x−8.
Substitute x=9: Now we need to evaluate the derivative at x=9 to find the slope of the tangent line at that point.
Calculate Result: Substitute x=9 into the derivative to get f′(9)=18(9)−8.
Calculate Result: Substitute x=9 into the derivative to get f′(9)=18(9)−8. Calculate f′(9)=162−8.
Calculate Result: Substitute x=9 into the derivative to get f′(9)=18(9)−8.Calculate f′(9)=162−8.The result is f′(9)=154. This is the slope of the tangent line at x=9.
More problems from Find the slope of a tangent line using limits