Question

已知x平方减6xy加9xy平方减2分之3x加2分之9y加2分之m是完全平方式,求m的值

Answer 1

x²-6xy+9xy²-3x/2+9y/2+m/2

错了吧

应该是x²-6xy+9y²-3x/2+9y/2+m/2

=(x-3y)²-(3/2)(x-3y)+m/2

=(x-3y)²-(3/2)(x-3y)+9/16-9/16+m/2

=(x-3y-3/4)²-9/16+m/2是完全平方式

所以-9/16+m/2=0

m=9/8