|3x+2y|=0,根号下（2x-3y+13）等于0所以3x+2y=0①2x-3y+13=0②①×3+②×2,得9x+4x=-26,解得x=-2代入①,解得y=3x^2-3xy-4y^2=(x-4y)(x+y)=(-2-12)×(-2+3)=-14已知|x+y|+（2x-y+3）^2=0则x+y=02x-y+3=0两式联立,解得...这么牛！呵呵