Let f(x) = √(9 - x).
a. Find the slope of the secant line to f(x) through the points (5, f(5)) and (8, f(8)).
b. Using the definition of the derivative, find the slope of the tangent line to the curve at the point (5, f(-5)).
c. Write the equation of the tangent line to the curve at the point (5, f(-5)).