(3x+1)(-2x+5)
=-6x^2-2x+15x+5
=-6x^2+13x+5
n=5
m=13x/5m=几，直接点你题目写的是-6x^2+mn+n?m=13x/5不好意思-6x^2+mx+n再帮忙算一下，我就采纳你m=13