Question

Find k such that the line y = 2x + 18 is tangent to the graph of the function below.
y=k√x

k=?

Answer 1

I told you, take derivative of the curve \(y = k\sqrt x\), what do you get?

Answer 2

1/2k^-1/2

Answer 3

you want y=2x+8 and y=ksqrt(x) to have a common point (a,f(a))
and you also want the derivative of 2x+8 to be equal to the derivative of ksqrt(x) at (a,f(a))