若x+y^2-8y-6y+25=0,试求3x+4y的值
问题描述:
若x+y^2-8y-6y+25=0,试求3x+4y的值
xiexie!
答
x²+y²-8x-6y+25=0
x²-8x+16+y²-6x+9=0
(x-4)²+(y-3)²=0
平方数不小于0
x-4=0,y-3=0
x=4,y=3
3x+4y=3*4+4*3=24