$24+\left(-18\right)-\left(-17\right)-63$

$-9r^4\:\left(-9\right)\:r^3$

$48y-18$

$\lim_{x\to0}\left(\frac{4x\cdot\cos\left(5x\right)-1}{sin\left(3x\right)-3x}\right)$

$9ab+6ab$

$\lim_{x\to0}\left(\left(9\sin\left(x\right)\right)^{5\tan\left(x\right)}\right)$

$\frac{dx}{x}+\frac{dy}{ylny}=0$