$y'+4xy-5xy^2=0$

$\left(\frac{1}{9}.\frac{4}{8}.\frac{18}{5}\right)^{-2}$

$\frac{\sin\left(a+x\right)}{cos\left(a\right)cos\left(x\right)}$

$3x+7\ge2x-3$

$\frac{d}{dx}\left(-3x^4y^3+5x^2-2y^2\right)=9-7xy$

$\frac{8x^2-22x-21}{4x+3}$

$\left(x-2y+4\right)\left(x+2y-4\right)$