a²+b²等于多少?若(x+y)²=23,(x-y)²=15,则xy的值为________，x²+y²的值为____________

a²+b²等于多少?若(x+y)²=23,(x-y)²=15,则xy的值为________，x²+y²的值为____________
a²+b²等于多少?
若(x+y)²=23,(x-y)²=15,则xy的值为________，x²+y²的值为____________

a²+b²等于多少?若(x+y)²=23,(x-y)²=15,则xy的值为________，x²+y²的值为____________
a²+b²
已是最简式不能再化简.