x减,y等于二x y等于四括号x加y括号平方等于多少?

2026-05-19 12:45:36
推荐回答(2个)
回答1:

x-y=2
xy=4
(x+y)^2=x^2+2xy+y^2
=x^2-2xy+y^2+4xy
=(x-y)^2+4xy
=4+4*4
=20

回答2: