(2mx^2-x^2+3x+1)-[-(5x^2+4y^2)+3x] =2mx^2-x^2+3x+1-(-5x^2-4y^2+3x) =2mx^2-x^2+3x+1+5x^2+4y^2-3x =2mx^2+4x^2+4y^2+1 =x^2(2m+4)+4y^2+1 ∵与x的值无关 ∴2m+4=0 ∴m=2 把m=2代入3m^2-[2m^2-(4m+5)+m]=15
分解代数式,得m=3,最后结果26