梦涵未来：(x³+mx+n)×(x²-5x+3)=x^5-5x⁴+3x³+mx³-5mx²+3mx+nx²-5nx+3n=x^5-5x⁴+(3+m)x³+(n-5m)x²+(3m-5n)x+3n∵结果不含x³和x²项∴含x³和x&su...