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If ∫(x)5(x)7+x6dx=alog⁡∣xk1+xk∣+C\int \frac{(\sqrt{x})^5}{(\sqrt{x})^7+x^6} dx = a\log\left|\frac{x^k}{1+x^k}\right| + C; Where C is an arbitrary constant, then the value of a.ka.k is:

Solution

✅ Correct Option: 3

The integrand is x5/2x7/2+x6=x5/2x7/2(1+x5/2)=1x(1+x5/2)\frac{x^{5/2}}{x^{7/2}+x^{6}}=\frac{x^{5/2}}{x^{7/2}(1+x^{5/2})}=\frac{1}{x(1+x^{5/2})}.

Using the standard result ∫dxx(1+xn)=1nlog⁡∣xn1+xn∣+C\int\frac{dx}{x(1+x^{n})}=\frac{1}{n}\log\left|\frac{x^{n}}{1+x^{n}}\right|+C with n=52n=\frac52:

a=25a=\frac{2}{5}, k=52k=\frac{5}{2}, so ak=1ak=1.

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