8. a) 5+3x=-4x-9
3x+4x=-9-5
7x=-14
x=-2
b)2x+3/2x+5=x+3/x+1
2x+3/2x+5=x+3/x+1
unde x≠5/2 si x≠-1
(2x+3)*(x+1)=(x+3)*(2x+5)
2x²+2x+3x+3=2x²+5x+6x+15
2x+3x+3=5x+6x+15
5x+3=11x+15
5x-11x=15-3
-6x=12
x=-2
c) (5-√7)x-√28=-10
(5-√7)x=-10+√28
x=-10+√28/5-√7
x=-10+2√7/50-√7
x=2(-5+√7)/5-√7
x=2*(-1)
x=-2
d) 2,5x=3(2+1,5x)-2
2,5=6+4,5x-2
2,5x=4+4,5x
2,5-4,5x=4
-2x=4
x=-2
9. a) 7x-11=x+13
7x-x=13+11
6x=24
x=4
b)(2+√3)x-4+2√3=0
(2+√3)x=4-2√3
x=4-2√3/2+√3
x=2(2-√3)*(2-√3)
x=2(2-√3)²
x=2(4-4√3+3)
x=2(7-4√3)
x=15-8√3
c) 10(x-3)+2=4(7+6x)
10x-30+2=28+24x
10x-28=28+24x
10x-24x=28+28
-14x=56
x=-2
d) 3(2x+3)-9=4-2(3x+2)
6x+9-9x=3-6x-4
-3x+9=-6x
-3x+6x=-9
3x=-9
x=-3
10. a) 4(3-x)+2=3(x-1)-4
12-4x+2=3x-3-4
14-4x=3x-7
-4x-3x=-7-14
-7x=-21
x=3
b) 5(x-1)+x=3(2x-5)
5x-5+x=6x-15
6x-5=6x-15
-5=-15
x ∈ Ø
11. a) x+3/2-1/2=1-2x+7/10
5(x+3)-5=10-(2x+7)
5x+15-5=10-2x-7â5x+10=3-2x
5x+2x=3-10
7x=-7
x=-1
b) x-5/2+4-x/3+x-3/4=5-x/4+4-x/3+3-x/2
x-5/2+x-3/4=5-x/4+3-x/2
2(x-5)+x-3=5-x+2(3-x)
2x-10+x-3=5-x+6-2x
3x-13=11-3x
3x+3x=11+13
6x=24
x=4
12. a) x+2/x+5=x-2/x-1
(x+2)*(x-1)=(x-2)*(x+5)
x²-x+2x-2=x²+5x-2x-10
-x+2x-2=5x-2x-10
x-2=3x-10
x-3x=-10+2
-2x=-8
x=4
b)
2x+5-3(x+2)/2(x+!)=3_2x/5+4x
2x+5-3x-6/2(x-1)=3-2x/5+4x
-x-1/2(x+1)=3-2x/5+4x
-(x+1)/2(x+1)=3-2x/5+4x
-1/=3-2x/5+4x
-(5+4x)=2(3-2x)
-5-4x=6-4x
-5=6
x ∈ Ø
c) (x-1)(x+1)-4=x*(x+5)
x^2-1-4=x^2+5x
-1-4=5x
-5=5x
5x=-5
x=-1
d)(x-2)^2+4=(x+1)^2+x
x^2-4x+4+4=x^2+2x+1+x
-4x+4+4=2x+1+x
-4x+8=3x+1
-4x-3x=1+8
-7x=-7
x=1
