Evaluate: \(\int\frac{e^x(1 + x)}{\cos^2(xe^x)}\,dx\)
Q.14 Evaluate: \(\int\frac{e^x(1 + x)}{\cos^2(xe^x)}\,dx\)
Q.14 Evaluate: \(\int\frac{e^x(1 + x)}{\cos^2(xe^x)}\,dx\)
Best answer
Answer: \(\tan(xe^x) + c\)
Put \(xe^x = t\). Then \((xe^x + e^x)\,dx = dt\), i.e. \(e^x(1 + x)\,dx = dt\).
\(\int\frac{dt}{\cos^2 t} = \int\sec^2 t\,dt = \tan t + c = \tan(xe^x) + c\).
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