$\int\left(x+3\right)\cdot\cos\left(x^2+6x\right)dx$

$2\cdot3\cdot4:2\cdot6$

$7^{12}\:x\:7^4$

$\left(g-2h\right)\left(g-3h\right)$

$\left(2x-y\right)^2-\left(x+5\right)^2\:$

$4\left(x+2\right)-3\left(x-6\right)$

$100:\left(-50\right).\left(-1\right)-\left(+20\right):\left(-10\right)+\left(-6+5\right):\left(-1\right)$