2.a)4+x=0
x=0-4
x=-4
b)12-x=16
x=16-12
x=4
c)-5x=20
x=20:5
x=4
d)4x-3=-15
4x=-15+3
4x=-12
x=-12:4
x=-3
e)5+2x<[sau egal]7
2x<[sau egal]7-5
2x<[sau egal]2
x<[sau egal ]2:2
x<[sau egal]1
f)2x+3=4+2x
2x-2x=4-3
0=1
Ceea ce e fals,deoarece ecuația nu are nicio soluție.
3)a=2•3-4•5+6•5-7•8
a=6-20+30-56
a=-14+(-26)
a=-14-26
a=-12
b=|-5+7|•|10-14|:(-2)
b=5-7•(-10)+14 :(-2)
b=5+70-7
b=68
