$15\left(x-y\right)$

$\frac{x^61}{x-1}$

$-2x^2+7x^3+42x^2-160x+275$

$\left(1-\cos\left(2x\right)\right)^2$

$4\cos^2\left(x\right)\tan\left(x\right)=3$

$\frac{-56x^{12}y^{0}}{4x^{5}y^{4}}$

$\left(+6\right).\:\left(-8\right)\:+\:\left(-5\right).\left(+6\right)\:-\:\left(+7\right).\left(-9\right)$