$\frac{d^2}{dx^2}\left(27\ln\left(7\right)x^2+27x^2ln\left(x\right)+9x^2\right)$

$( 4 p q - 3 q ) ^ { 2 }$

$1.6\cdot10$

$u^2+24u=35$

$\left(-4cx^2-5c+2c^2x^2\right)\left(-2cx^3\right)\left(2cx\right)$

$-15+6x-19-20x$

$21:\left(-7\right)+10\cdot\left(-2\right)+9\cdot4-15\cdot3$