X²+4x-3=0
x1+x2=-4 U x1*x2=-3
1)1/x1+1/x2=(x2+x1)/x1x2=-4/(-3)=4/3
2)x1²x2+x1x2²=x1x2*(x1+x2)=-3*(-4)=12
3)x1²+x2²=(x1+x2)²-2x1x2=(-4)²-2*(-3)=16+6=22
4)x1/x2+x2/x1=(x1²+x2²)/x1x2=22/(-3)=-22/3
5)1/x1²+1/x2²=(x2²+x1²)/x1²x1²=22/9
6)(x1-x2)²=x1²-2x1x2+x2²=22-2*(-3)=22+6=28