a) Ta có:
3x + 2012 = 2015
3x = 2015 - 2012
3x = 3
x = 3 : 3
x = 1
Vậy x = 1
b) Ta có:
5x - 12 = 32 .52
5x - 12 = 468
5x = 480
x = 96
Vậy x = 96
c) Ta có:
2012 - (2013 - x) = 12
2013 - x = 2000
x = 13
Vậy x = 13
d) Ta có:
2002 : [12+(2x-20)] = 91
12+(2x-20) = 22
2x-20 = 10
2x = 30
x = 15
Vậy x = 15
A) 3X + 2012 = 2015
3X = 2015 - 2012
3X = 3
X = 3 : 3
X = 1
B) 5X - 12=3^2.52
5X - 12 = 9.52
5X - 12 = 468
5X = 468 + 12
5X = 480
X = 480 : 5
X = 96
C) 2012 - ( 2013 - X) = 12
2013 - X = 2012 - 12
2013 - X = 2010
X = 2013 - 2010
X = 3
D) 2002 : [12+(2X-20)]=91
12+(2X-20)= 2002 : 91
12+(2X-20)= 22
2X-20=22-12
2X-20=10
2X=10+20
2X=30
X=30:2
X=15