$x\left(\frac{\left(144-3x^2\right)}{4}\right)$

$\frac{1}{\tan^2x}-\cos^2x=\cos^2x\cdot\cot^2x$

$3x^4+9x^3$

$a+6\cdot a+8$

$\frac{1}{sin^2x}-\frac{1}{1-cosx}=\frac{2+cosx}{sin^2x}$

$\frac{3}{4}x^2+\frac{2}{3}y^2-\frac{1}{3}xy+\frac{1}{9}y^2+\frac{1}{9}y^2+\frac{1}{6}xy-\frac{1}{3}y^2$