Use the definition to find an expression for the instantaneous velocity of an object moving with rectilinear motion according to the given function relating s and t.

s=9t+12

The expression for the instantaneous velocity of the object is

Find an equation for the line tangent to the curve y=2x2+5 at the point (2,13). Sketch the curve and the tangent line.

The equation of the tangent line is y=_____