对于ax^5+bx^3+cx-5取x=m时，结果为am^5+bm^3+cm-5取x=-m时，结果为-am^5-bm^3-cm-5（即ax^5+bx^3+cx，当x=m或-m时，得相反数）即当x=-7时，ax^5+bx^3+cx=12则当x=7时，ax^5+bx^3+cx=-12当x=7时，ax^5+bx^3+cx-5=-17
