已知m,x,y满足1.2/3(x-5)^2+5|m|=0
x-5=0 m=0
x=5 m=0
2.-2a^2b^y+1与7a^3b^2是同类项.
2+y+1=3+2
y=2
代数式2x^2-6y^2+m(xy-9y^2)-(3x^2-3xy+7y^2)的值.
=2x^2-6y^2+0*m(xy-9y^2)-3x^2+3xy-7y^2
=-13y^2-x^2+3xy
=-13*2^2-5^2+3*5*2
=-52-25+30
=-47