Use a limit definition of the derivative to find the slope of the tangent line to the curve f(x) = 6x at x = 2. Given function f(x) = 6 + 3x - ! = 6 + 3x 5x, use a limit definition of the derivative to evaluate f'(4). Given function f(x) fraction. = 2 use a imit definition of the derivative to evaluate f'(5) as a reduced x