$\sec\left(x\right)\left(1-\cos\left(2x\right)\right)=\frac{2}{\cot^2\left(x\right)}$

$\left(7x^4+1\right)^2$

$\left(12b^4\right)^2$

$\int\frac{6}{\left(1+x^2\right)^3}dx$

$12x^2-5^4$

$\int\frac{x^3-6x^2+x-4}{1-x^4}dx$

$\left(-48\right):\left(-4\right).\left(-3\right):\left(-6\right)$