$0.09x^2+0.12xy+0.04y^2$

$y'=\left(1+x^2\right)\left(1+y^2\right)$

$\left(60^2\right)+\left(30^2\right)$

$x\cdot\cos\left(2y\right)-x^3y^2+\frac{\sin\:\left(2y\right)}{2}$

$16m^2-25m^2n^2+9m^4$

$\frac{1}{1+\cos\left(x\right)}+\frac{\cos\left(x\right)}{1-\cos\left(x\right)}$

$2^3.5^3$