①已知x^2+4y^2+6x-4y+10=0,求xy ②已知a^2-6a+b^2-6b+18=0,求a+b
问题描述:
①已知x^2+4y^2+6x-4y+10=0,求xy ②已知a^2-6a+b^2-6b+18=0,求a+b
答
x^2+4y^2+6x-4y+10=0(x²+6x+9)+(4y²-4y+1)=0(x+3)²+(2y-1)²=0x+3=0,2y-1=0x=-3,y=½xy=-3/2a^2-6a+b^2-6b+18=0(a²-6a+9)+(b²-6b+9)=0(a-3)²+(b-3)²=0a-3=0,b-3=0a=...