解
相加的結(jié)果是單項(xiàng)式
∴
3x²y^m與-2x^ny³是同類項(xiàng)
∴n=2,m=3
∴3x²y³+(-2x²y³)
=(3-2)x²y³
=x²y³確定是對(duì)的？確定已知關(guān)于x，y的多項(xiàng)式mx‘3+3nxy’2+2x‘3-xy’2+y合并后不含三次項(xiàng)，求2m+3n的值。mx³+3nxy²+2x³-xy²+y=(m+2)x³+(3n-1)xy²+y不含三次∴m+2=03n-1=0∴m=-2n=1/3∴2m+3n=2×(-2)+3×(1/3)=-4+1=-3有其他問(wèn)題采納后求助