$\left(-5\right).4+3.\left(-10\right)$

$\left(x-1\right)-\left(x-1\right)^2$

$12\cdot\left(-1\right)\cdot\left(-2\right)$

$-1-6\left(-10\right)$

$\sec\left(2x\right)-\tan\left(2x\right)=\frac{\cos\left(x\right)-\sin\left(x\right)}{\sin\left(x\right)+\cos\left(x\right)}$

$7a\:-\:\:1,8\:b\:+\:5\:c\:-\:7,2a\:+\:5a\:-\:6,1b\:-\:8a\:+\:12b\:\:$

$\lim_{x\to0}\left(\frac{log\left(1+sin6x\right)}{3x}\right)$