当x=-3时,多项式ax5+bx3+cx-5的值等于7,则当x=3时,多项式ax5+bx3+cx-5的值等于( ) A.17 B.19 C.-17 D.-19
问题描述:
当x=-3时,多项式ax5+bx3+cx-5的值等于7,则当x=3时,多项式ax5+bx3+cx-5的值等于( )
A. 17
B. 19
C. -17
D. -19
答
∵x=-3时,ax5+bx3+cx-5=7即ax5+bx3+cx=12,
∴x=3时,ax5+bx3+cx=-12,
∴ax5+bx3+cx-5=-12-5=-17.
故选:C.