$x-1\le2$

$\frac{\left(sin\left(6x\right)-sin\left(2x\right)\right)}{\left(cos\left(6x\right)-cos\left(2x\right)\right)}$

$21x^6y^3+\:7x^2y$

$sin\left(arctan\left(\frac{x}{3}\right)\right)$

$9y^2+48y+64$

$2\cdot\cos^2\left(x\right)-\cos\left(2\cdot x\right)=1$

$\left(+4\right).\left(+2\right)-\left(-5\right):\left(+5\right)$