当x= 1; 3; 5; 0.5 1/3; 3/2; -2; -1.5
当y= 0.5; 2; -2; -2; 3; -3; 4; 5
2x-3y=2 0 16 7 -25/3 12 -16 -18
x的平方-1/2y= 0.75 8 26 1.25 -18/25 2 -0.25
(x+y)*(x-y)= 0.75 5 21 -3.75 -23/8 -27/4 -12 -22.5
(2x+y)/(2x-y)=5/3 2 2/3 -1/3 -5/4 0 0 -16