Tìm số nguyên x, biết a) (-12).x = (-15).(-4) -12 b) (-9).x +3 = (-2).(-7) +16 c) (-12).x -34 = 2

* Hướng dẫn giải

a)

$\begin{array}{l}\left(-12\right).x=\left(-15\right).\left(-4\right)-12\\ \left(-12\right).x=60-12\\ \left(-12\right).x=48\\ x=48:\left(-12\right)\\ x=-4\end{array}$

b) 

$\begin{array}{l}\left(-9\right).x+3=\left(-2\right).\left(-7\right)+16\\ \left(-9\right).x+3=14+16\\ \left(-9\right).x+3=30\\ \left(-9\right).x=30-3\\ \left(-9\right).x=27\\ x=27:\left(-9\right)\\ x=-3\end{array}$

c)

$\begin{array}{l}\left(-12\right).x-34=2\\ \left(-12\right).x=2+34\\ \left(-12\right).x=36\\ x=36:\left(-12\right)\\ x=-3\end{array}$