$\left|x\right|^6\cdot\left|x\right|^n$

$\left(x+y\right)a^3+\left(x+y\right)b^2$

$\left(a+7\right)\left(a-1\right)$

$\left(12x-9y\right)\left(12x+9y\right)$

$\lim\:_{x\to\:\infty\:}\left(\frac{3x^2+5}{x^2+1}\right)^{\frac{x+1}{2x}}$

$2x\tan\left(y\right)dx+\sec\left(y\right)^2dy=0$

$5x^6y^3dx+\frac{15}{7}x^7y^2dy=0$