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

$\sin\left(90-x\right)=\cos\left(x\right)$

$5^{2^{3^0}}\:\:+\:\left(\left(5^2\right)^3\right)^0$

$12x^2+5x-2=0$

$\left(4x^3+5x^2y^3\right)\left(5x^2+y^5z^2\right)$

$\left(3+8y^2\right)\left(3-8y^2\right)$

$\left(2b+4a+3c+11\right)+\left(12a-18b-15c\right)$