$\left(a+5\right)\left(a-5\right)-a\left(a-1\right)$

$\left(x+2\right)\left(x^2-2x+1\right)$

$4t^2-9s^2$

$\int\frac{ln\left(7x\right)}{x^4}dx$

$\left(x\:+2\right)\left(7x\:-2\right)$

$\left(2.6\right).\left(4.9\right)$

$\int\left(3x+1\right)\left(x-4\right)^{\frac{5}{2}}dx$