Question

1.(因式分解)m*m/9-mn/3+n*n/4.2.已知x*x+y*y-2x+1=0,求xy=________.

Answer 1

1、m*m/9-mn/3+n*n/4

原式=（m／3）²-2×（m／3）n/2+（n/2）²

=（m／3-n/2）²

.2.已知x*x+y*y-2x+1=0,求xy

∵x*x+y*y-2x+1=0

∴（X-1）²+Y²=0

∴X=1,Y=0

把X=1,Y=0代入xy=1×0=0

3.已知x*x+4x+4+y*y-8y+16=0,求x/y的值

∵x*x+4x+4+y*y-8y+16=0

∴（X+2）²+（Y-4）²=0

∴X+2=0,Y-4=0

∴X=-2,Y=4

把X=-2,Y=4代入x/y=-2／4=-1／2