已知x²+y²-2x+4y+5=0,求x²-9y²/x²+6xy+9y²的值
问题描述:
已知x²+y²-2x+4y+5=0,求x²-9y²/x²+6xy+9y²的值
答
x²+y²-2x+4y+5=0(x-1)²+(y+2)²=0x-1=0 y+2=0x=1 y= -2(x²-9y²)/(x²+6xy+9y²)=(x-3y)(x+3y)/(x+3y)²=(x-3y)/(x+3y)=(1+6)/(1-6)= -7/5...