$\left(x+1\right)\left(x-1\right)\left(x-4\right)\left(x-6\right)$

$\left(-3\right)-\left(-2\right)+\left(-6\right)+\left[\left(-15\right)+18\right]$

$\lim_{x\to0}\left(\frac{6x^2}{secx-1}\right)$

$2x^2+y^2-7=0$

$60\sqrt{24}$

$\frac{\left(y-1\right)\left(y^2+2y-3\right)}{y^2-2y+1}$

$\lim_{x\to\infty}\left(\frac{3x^2-7x+2}{9x-5}\right)$