x,y是二元一次方程组2x-3y=13,3x+2y=0的解可求出：
x=2,y=-3
所以(2x+y)^2-2(2x+y)(x-y)+(x-y)^2
=【(2x+y)-(x-y)】^2
=(x+2y)^2
=(2-2×3)^2
=16