已知x+y=6,xy=7,试求x^2+y^2的值要过程写纸上七下数学

2025-05-18 09:24:13
推荐回答(2个)
回答1:

回答2:

x^2+y^2
=x^2+2xy+y^2-2xy
=(x+y)^2-2xy
=6^2-2×7
=22