Understand derivative as instantaneous slope of a curve.
slope ≈ (f(x+h) − f(x−h)) / 2h
tangent line: y = f(x₀) + slope · (x − x₀)
Find slope ≈ 0
Find slope > 2
Find negative slope
Move x₀ to a point where the slope is nearly flat (close to zero). Try the quadratic function.
Ready to check