x=3
ax^5+bx^3+cx+9
=a*3^5+b*3^3+c*3+9
=81
a*3^5+b*3^3+c*3=72
x=-3
原式=(-a*3^5)+(-b*3^3)+(-c*3)+9
=-(a*3^5+b*3^3+c*3)+9
=-72+9
=-63