Răspuns :
Răspuns:
5)
a) x+2a+2b=20
x+2(a+b)=20
x+16=20
x=20-16=4
b) 5a+5b-x=12
5(a+b)-x=12
40-x=12
x=40-12=28
c) x+6=23+7a+7b
x+6=23+7(a+b)
x=-6+23+56
x=73
6)a) 6a-8b=2(3a-4b)
b) 3*9+4*9-7*2=9(3+4)-7*2
=9*7-7*2=7(9-2)=7*7=49
7)
a)x-2a+2b=11/*(-1)
-x+2a-2b=-11
-x+2*17=-11
-x=-34-11
X=45
b) 2b-2a+x=45
2(b-a)+x=45
34+x=45
x=11
Răspuns:
a) x+2a+2b=20
x+2(a+b)=20
x+2·8=20
x=20-16=>x=4
b) 5a+5b-x=12
5(a+b)-x=12
40-x=12
x=40-12=>x=28
c) x+6=23+7a+7b
x+6=23+7(a+b)
x=23-6+7·8
x=17+56=>x=73
6) a) 6a-8b=2(3a-4b)
b) 3·9+4·9-7·2=9·(3+4)-7·2
=9·7-7·2=7·(9-2)=7·7=49
7) a) x-2a+2b=11
x-2·(a-b)=11
x-2·17=11
x-34=11=>
x=34+11=>x=45
b) 2b-2a+X=45
2(a-b)+x=45
2·17+x=45
x=45-34=>x=11