Răspuns:
Explicație pas cu pas:
17. a)( x + 3 )(y - 1 ) = 0
x+3=0=>x=-3
y-1=0=>y=1
b)x(y-2)=-7=>produsul,celor,doi,termeni=(-7)
Pentru,x=(-7)=>y-2=1;y=3
Pentru,(y-2)=(-7),adica,y=(-5)=>x=1
18. a) 3•x - 17 = 2
3x = 2 + 17
3x = 19
x = 19/3 ∉ Z
b) -5x +14 = 27
14 - 27 = 5x
- 13 = 5x
x = - 13/5 ∉ Z
c) x + 3 = 4x - 7
3 + 7 = 4x - x
10 = 3x
x = 10/3 ∉ Z
d) -72 : (x + 1) = 14
- 72 = 14(x + 1)
- 72 = 14x + 14
- 72 - 14 = 14x
- 86 = 14x
x = - 86/14
x = - 43/7 ∉ Z
19. -x= 3-2
x=-1
3x=2+7
3x=9
x=3
4x+3x=12+2
7x=14
x=2
termenii se trec dintr-o parte in alta ,schimbandu-le semn
20.a) 2-(x+1)=-7(x+3)+3(3x-5)-5 =
2-x-1=-7x-21+9x-15-5=
1-x=2x-41=
-x-2x=-41-1=
-3x=-42=
x=14
b)-3*(3x+1)+14=3(7x-3)-10=
-9x-3+14=21x-9-10=
-9x+11=21x-19=
-9x-21x+-19-11
-30x=-30
x=1
c)a sati scriu de la primu egal
16-(3-2x+6)impartit2=37
16-(9-2x)impartit2=37
16-(9-2x)/2=37
32-(9-2x)=74
32-9+2x=74
23+2x=74
2x=74-23
2x=51
x=51/2 sau 25,5
d)
4-[6-(-3-3-5-x-7)-9]=1
4-[6-(-18-x)-9)=1
4-(6+18+x-9)=1
4-(15+x)=1
4-15-x=1
-11-x=1
-x=1+11
-x+12
x=-12
e)
35x-5+2x+2=-7x-21+9x-15+43
37x-3+2x+7
37x-2x=3+7
35x=10
x=2/7 sau 0,28
21.c) 3|x+1|+5=|x+1|+11
2|x+1|=6
x+1=3 sau -3
x=2, -4
d)-4|2x-1|+2=-|2x-1|-7
-3|2x-1|=-9
2x-1=3 sau -3
2x=4 say -2
x=2, -1
22.a) x=7, x= -7 b) x=5, x= -5 c) nu are solutii d) x=5, x= -1 e) x=10, x= -4 f) x=7, x= -7 g) x=7, x= -4 h) x=11, x= -9 i) x=10, x= -2
