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

$\int\:\frac{\cos\left(\sqrt{x}\right)}{\sqrt{x}\cdot sen\sqrt{x}}$

$\lim_{x\to2}\frac{cos\left(x+\frac{\pi}{2}-2\right)}{ln\left(x-1\right)}$

$\frac{x^3+x+1}{x^4+2x^2+1}$

$( a - b x ) ( a + b x )$

$\frac{\sec0\tan0}{\sin0}=\sec^20$

$x^2-2x-35=0$