Question
Integrate the function $\int {\frac{{{{\sin }^8}x - {{\cos }^8}x}}{{1 - 2{{\sin }^2}x{{\cos }^2}x}}} dx$

Answer

$\int {\frac{{{{\left( {{{\sin }^4}x} \right)}^2} - {{\left( {{{\cos }^4}x} \right)}^2}}}{{1 - 2{{\sin }^2}x.{{\cos }^2}x}}} dx$

=$\int {\frac{{\left( {{{\sin }^4}x + {{\cos }^4}x} \right)\left( {{{\sin }^2}x + {{\cos }^2}x} \right)\left( {{{\sin }^2}x - {{\cos }^2}x} \right)}}{{1 - 2{{\sin }^2}x.{{\cos }^2}x}}} dx$

=$\int {\frac{{\left( {1 - 2{{\sin }^2}x.{{\cos }^2}x} \right)\left( {{{\sin }^2}x - {{\cos }^2}x} \right)}}{{\left( {1 - 2{{\sin }^2}x.{{\cos }^2}x} \right)}}} dx$

=$\int { \left( {{{\sin }^2}x - {{\cos }^2}x} \right)} dx$

=$\int { - \cos 2xdx} $

=$- \frac{{\sin 2x}}{2} + c$

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