Estimate the slope of the tangent line rate of change to f x x at x 1 by finding slopes of secant lines through 1 1 and each of the following points on the graph of f x x 10 9 8 7 6 5 a 2 4 10 9 8 7 4 3 9 secant slope msec b 1 5 2 25 10 9 8 secant slope msec