Derivation Of Composite Trapezoidal Rule
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Derivation Of Composite Trapezoidal Rule : b Let us find the value of ∫ f(x) dx a numerically by composite trapezoidal rule. Solution : Let [a,b] be divided into n equal sub intervals of length h each . Let a= x₀,x₁,x₂,.......xₙ=b be the points of sub division . i.e x₁ = x₀+ih for i= 0,1,2,......n By Newton's Forward Difference Interpolation f(x) = f(x₀)+uΔf(x₀) +u(u-1)/2! Δ²f(x₀)+........ where x = x₀+uh b ∫ f(x) dx = a xₙ ∫ [f(x₀)+uΔf(x₀)+u(u-1)/2! Δ²f(x₀)+...]dx x₀ n = h∫ [f(x₀)+uΔf(x₀)+u(u-1)/2 Δ²f(x₀)+...]dx 0 =h[uf(x₀) +u²/2 Δf(x₀) + n (u³/6 -u²/4)Δ²f