find the values of k such that the line y = 5x -4 is tangent to the function f(x) = x^2 - kx

Question

matt101 · Answer

Do you know how to find derivatives?

matt101 · Answer

I'll assume that you do unless you say otherwise...

A tangent line is a straight line that touches a function at exactly one point, and therefore represents the slope of the function at that point. In our case, the slope of the tangent line is 5.

The first derivative of our function is f'(x) = 2x - k. We want our slope to be 5, so f'(x) = 5. That means 5 = 2x - k  -->  k = 2x - 5.

anonymous · Answer

thanks!

matt101 · Answer

No problem - glad I could help!