$2x^4-15x^3+7x^2+72x-36$

$\frac{-x^2+1}{x^2-4}$

$\int_2^4\left(9x+4\right)dx$

$.\:\left(+2\right)\:-\:\left(+8\right)\:+\:\left(-5\right)\:-\:\left(-3\right)\:-\left(+1\right)$

$7x^2-x+4\cdot x$

$\int x ^ { 7 } \sqrt { 9 - x ^ { 4 } } d x$

$\frac{dy}{dx}=\frac{\left(2x-y\right)}{\left(x-y\right)}$