Răspunsuri

2014-11-10T18:23:38+02:00
A)2x+3=x+8
2x-x=8-3
x=5=>x∈N
b)2x+3=2(x+1)
2x+3=2x+2
2x-2x=2-3
x=-1=>x∉N
c)3(x+1)=3(x+2)-3
3x+3=3x+6-3
3x-3x=6-3-3
x=0=>x∈N
d)2x+7=43+x
2x-x=43-7
x=36
e)84:(x-3)=12
x-3=84·12
x-3=1008
x=1008+3
x=1011
f)3(4+5x)=72
12+15x=72
15x=72-12
15x=60
x= \frac{60}{15}
x=4