(1)
(2x+y)²-2(2x+y)(x-y)+(x-y)²
=[(2x+y)-(x-y)]²
=(x+2y)²
(2)
2x-3y=13 ...(1)
3x+2y=0 ...(2)
(1)x2+(2)x3
4x+9x=26
x=2 代入(2)
y=-3
(1)
(2x+y)²-2(2x+y)(x-y)+(x-y)²
=[(2x+y)-(x-y)]²
=(x+2y)²
(2)
2x-3y=13 ...(1)
3x+2y=0 ...(2)
(1)x2+(2)x3
4x+9x=26
x=2 代入(2)
y=-3