$-x^2-6x-18$

$\left(2x-3\right)^2+x^2+6=\left(3x+1\right)\left(3x-1\right)$

$-0.75+\left|\left(\frac{\sqrt{16}}{\sqrt{25}}\right)-0.2\right|+\frac{2}{3}\cdot\left(\frac{1}{4}\right)^2$

$\frac{dy}{dx}=\frac{5y}{\left(x+7\right)}$

$5x^228y$

$x+2+-4x^2+16x+6$

$\left(-7\right)-\left(+2\right)+\left(+8\right)-\left(-4\right)$