Question

解方程组：﹛x平方+2xy+y平方=9 ﹛（x-y)平方-3（x-y)+2=0

Answer 1

x²+2xy+y²=9

(x+y)²=9

x+y=±3

(x-y)²-3(x-y)+2=0

(x-y-1)(x-y-2)=0

x-y-1=0 x-y-2=0

x-y=1 x-y=2

{x+y=3 x-y=1}解得x=2 y=1

{x+y=3 x-y=2 }解得 x=5/2 y=1/2

{x+y=-3 x-y=1}解得x=-1 y=-2

{x+y=-3 x-y=2}解得x=-1/2 y=-5/2