Show your solution, Thank you!

12. The function f'(x) is defined by the formula f'(x) = lim h-0 13. (a) The derivative of f(x) = x is f'(x) =_ (b) The derivative of f(x) = vx is f (x) = _ 14. Suppose that the line 2x + 3y = 5 is tangent to the graph of y = f(x) at x = 1. The value of f(1) is . and the value of f'(1) is 15. Which theorem guarantees us that if f (xo + h) - f(xo) lim h-0 h exists, then lim f(x) = f(xo)