问题
填空题
若(x+y)2=26,(x-y)2=10,则xy=______.
答案
∵(x+y)2=x2+2xy+y2=26①,(x-y)2=x2-2xy+y2=10②,
∴①-②得:4xy=16,
解得:xy=4.
故答案为:4
若(x+y)2=26,(x-y)2=10,则xy=______.
∵(x+y)2=x2+2xy+y2=26①,(x-y)2=x2-2xy+y2=10②,
∴①-②得:4xy=16,
解得:xy=4.
故答案为:4