$\left(a^{x+1}-2b^{x+1}\right)\left(a^{x+1}+2b^{x+1}\right)$

$2xy^2-x^2$

$36\cdot36$

$200mn^3-50mn^2$

$\lim_{x\to\pi}-\frac{\left(sin\left(x\right)\right)}{\left(1-cos\left(x\right)\right)}$

$\lim_{x\to\infty}\:x\:ln\left(\frac{\left(x+a\right)}{\left(x-a\right)}\right)$

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