x1x2-x1-x2=1
(x1-1)(x2-1)=2
x1+x2-x1x2=2
(x1-1)(x2-1)=-1
x1x2+x1+x2=6
(x1+1)(x2+1)=7
x1x2-x1-x2=3
(x1-1)(x2-1)=4
x1+x2-2x1x2=3
(2x1-1)(x2-1/2)=7/2
x1x2-x1-x2=1
(x1-1)(x2-1)=2
x1+x2-x1x2=2
(x1-1)(x2-1)=-1
x1x2+x1+x2=6
(x1+1)(x2+1)=7
x1x2-x1-x2=3
(x1-1)(x2-1)=4
x1+x2-2x1x2=3
(2x1-1)(x2-1/2)=7/2