Understand definite integrals as a limit of Riemann sums.
Area ≈ Σ f(xᵢ) · Δx
Δx = (b − a) / n
Approximate x²
Reduce the error
Compare methods
Set f(x) = x², a = 0, b = 2, and use at least 20 rectangles. The true area is 2.667.
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