um^7+uh^7−hm^7−h^8=m^7(u-h)-h^7(u-h)=(m^7-h^7)(u-h)
th^5−tm−uh^5+dm+um−dh^5=h^5(t-u-d)-m(t-u-d)=(h^5-m)(t-u-d)
