$\frac{1+\sin\left(x\right)}{\cos\left(x\right)}-\frac{\cos\left(x\right)}{1+\sin\left(x\right)}=\frac{2}{\cos\left(x\right)}$

$5t=-45$

$\int\left(1+3x\right)^7dx$

$a^{10}-4a^5+4$

$\lim_{x\to0}\left(\frac{\cos\left(2x\right)-\cos\left(3x\right)}{2x}\right)$

$\left(124+23\right)-\left(-12+9\right)+123$

$x^4+x^2y^2+y^4+x^2y^2-x^2y^2-x^2y^2$