1.

Evaluate: ∫x3 sin2 x dx for x ∈ [-π/4,π/4]

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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