已知|x-y+4|与2(x+y)²互为相反数,则x²+y²的值是
问题描述:
已知|x-y+4|与2(x+y)²互为相反数,则x²+y²的值是
答
知|x-y+4|与2(x+y)²互为相反数,
|x-y+4|>=02(x+y)²>=0
所以
x-y+4=0
x+y=0
x=-2 y=2
x^2+y^2=8