a. 3x²-12=0
3(x²-4)=0
3(x-2)(x+2)=0
x1, x2=+/- 2
S={-2; 2}
b. 2x²-5x=0
x(2x-5)=0
x1=0
2x=5, x=5/2
x2=2,5
S={0; 2,5}
c. 5x²+8=0
x²=-8/5
S=Ф in R
d. 10x²=0
x²=0
S={0}
e. x²+x=0
x(x+1)=0
x1=0
x+1=0, x2=-1
S={-1; 0}
f. x²-0,99=1,01
x²=1,01+0,99
x²=2
S={-√2; √2}
g. 4x²-12x=0
4x(x-3)=0
x1=0
x2=3
S={0; 3}
h.3x²+√3x=0
x√3(x√3+1)=0
x1=0
x√3+1=0, x2=-1/√3=-√3/3
S={-√3/3; 0}
i. 2/3x²-1/3=0
1/3(2x²-1)=0
2x²-1=0
2x²=1
x²=1/2
x=+/-1/√2=+/-√2/2
S={-√2/2; √2/2}
