$\frac{d^2}{dx^2}\left(f\left(x\right)=\sqrt{x}e^{-x}\right)$

$\frac{81x^5}{9x^5}$

$-2\cdot45$

$\frac{\left(2x+1\right)\left(x-1\right)}{x\left(x^2-1\right)}$

$\frac{dy}{dx}+\frac{2y}{x}=\frac{4}{x}$

$-3a+17b^2+10b^2+19a^2-9a^2+19-13-12+2c^2+17c+9c-8c$

$\frac{\left(27x^2y^3-15x^4\right)}{\left(-3x^2\right)}$