2x^2+3x-4=0
a=2,b=3,c=-4
x1+x2=-b/2=-3/2
x1*x2=c/a=-4/2=-2
1/x1+1/x2=(x1+x2)/(x1x2)=3/4
x1^2+x2^2=(x1+x2)^2-2x1x2=9/4+4=25/4
(x1+1)(x2+1)=x1*x2+(x1+x2)+1=-2+(-3/2)+1=-5/2
|x1-x2|=|√(b^2-4ac)/a|=√41/2