$3a\cdot7a^2$

$\log_{10}\left(18\right)-\log_{10}\left(3x\right)=\log_{10}\left(2\right)$

$-4x^2+18x-47=-6x^2+34x-71$

$\int\cos\left(x\right)\tan\left(x\right)dx$

$9.6+-1.8$

$\lim_{x\to0}\left(\frac{7x+x^2}{x}\right)$

$\lim_{x\to-1}\left(\frac{4x^2+12x}{x^2+4x+4}\right)$