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Evaluate: ∫x3 sin2 x dx for x ∈ [-π/4,π/4] |
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Answer» Let f(x) = x3 sin2 x = x3 (sin x)2 ∴ f(- x) = (- x)3 (sin (- x))2 = (- x)3 (- sin x)2 = – x3 sin2 x = -f(x) f(-x) = -f(x) ∴ f(x) is an odd function. ∴ ∫x3 sin2 x dx for x ∈ [-π/4,π/4] = 0 (by property) |
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