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10 steps: (1) The derivative f'(x) = lim(h→0) [f(x+h)-f(x)]/h. (2) This is the slope of the tangent line at x. (3) Example: f(x)=x². (4) f(x+h) = (x+h)² = x²+2xh+h². (5) f(x+h)-f(x) = 2xh+h². (6) [f(x+h)-f(x)]/h = 2x+h. (7) lim(h→0) (2x+h) = 2x. (8) So f'(x) = 2x. At x=3, slope=6. (9) Notation: f'(x

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