由题意：
当x=3时
a*3^5+b*3^3+3c-6=17
所以a*3^5+b*3^3+3c=23
当x=-3时,
a*(-3)^5+b*(-3)^3+(-3)c-6
=-(a*3^5+b*3^3+3c)-6
=-23-6
=-29