$x^2+6x+15>0$

$-x+1+1$

$\lim_{x\to0}\left(\frac{2x\arctan\left(x\right)-\ln\left(1+x^2\right)-x^2}{x^2\left(1-\cos\left(x\right)\right)}\right)$

$\lim_{x\to0}\left(\frac{4sinxcosx-x}{tanx-x}\right)$

$\int_1^{x^2}e^{t^2}dt$

$-9m^3n^2-2.5m^3n^2$

$\left(\frac{2}{3}x^2-\frac{1}{3}\right)^3$