Problem

$\int_{0}^{3 \pi / 2} x \sin x d x$

Answer

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Answer

So, the definite integral of \(x \sin x\) from \(0\) to \(3 \pi / 2\) is \(\boxed{-1}\).

Steps

Step 1 :Given the integral problem \(\int_{0}^{3 \pi / 2} x \sin x d x\), we can solve this using the method of integration by parts.

Step 2 :The formula for integration by parts is \(\int udv = uv - \int vdu\).

Step 3 :Let's set \(u = x\) and \(dv = \sin(x) dx\).

Step 4 :We then find \(du\) and \(v\). \(du\) is the derivative of \(x\) which is \(dx\), and \(v\) is the integral of \(\sin(x)\) which is \(-\cos(x)\).

Step 5 :Substituting these into the formula, we get \(-x\cos(x) + \int \cos(x) dx\).

Step 6 :Evaluating the integral, we get \(-x\cos(x) + \sin(x)\).

Step 7 :Evaluating this from \(0\) to \(3 \pi / 2\), we get \(-1\).

Step 8 :So, the definite integral of \(x \sin x\) from \(0\) to \(3 \pi / 2\) is \(\boxed{-1}\).

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