Bài 1 : Tìm x
a, 18 . x = -90
x=-90 : 18
x= -5
b, ( -3 ) . ( x +12 ) = -36
x+12= -36 : (-3)
x+12= 12
x= 0
c, 2x - 13 = -37
2x = -37+13
2x=-24
x=-24 : 2
x=-12
d, ( 25 - x ) . 12 = - 24
25 - x = -24 : 12
25 -x = -2
x= 25+2
x=27
a/ \(18.x=-90\Leftrightarrow x=-\frac{90}{18}=-5\)
b/ \(\left(-3\right)\left(x+12\right)=-36\Leftrightarrow x+12=12\Leftrightarrow x=0\)
c/ \(2x-13=-37\Leftrightarrow2x=-24\Leftrightarrow x=-12\)
d/ \(\left(25-x\right)12=-24\Leftrightarrow25-x=2\Leftrightarrow x=23\)
KL: .....................
1 : Tìm x
a, 18 . x = -90
x=-90 : 18
x= -5
b, ( -3 ) . ( x +12 ) = -36
x+12= -36 : (-3)
x+12= 12
x= 0
c, 2x - 13 = -37
2x = -37+13
2x = -24
x = -24 : 2
x = -12
d, ( 25 - x ) . 12 = - 24
25 - x = -24 : 12
25 - x = -2
x = 25 + 2
x = 27