已知x-y=3,xy=10,xﾁ0ﾅ5+yﾁ0ﾅ5及(x+y)ﾁ0ﾅ5的值

已知x-y=3,xy=10,xﾁ0ﾅ5+yﾁ0ﾅ5及(x+y)ﾁ0ﾅ5的值
已知x-y=3,xy=10,xﾁ0ﾅ5+yﾁ0ﾅ5及(x+y)ﾁ0ﾅ5的值

已知x-y=3,xy=10,xﾁ0ﾅ5+yﾁ0ﾅ5及(x+y)ﾁ0ﾅ5的值
x²+y²
=(x²-2xy+y²)+2xy
=(x-y)²+2xy
=3²+2×10
=29
(x+y)²
=x²+2xy+y²
=(x²-2xy+y²)+4xy
=(x-y)²+4xy
=3²+4×10
=49

x的平方+y的平方
=(x-y)的平方+2xy
=3的平方+2×10
=29

(x+y)的平方
=(x-y)的平方+4xy
=3的平方+4×10
=49