题目内容
当x=2时,多项式ax5+bx3+cx-5的值为7,当x=-2时,这个多项式的值为( )
| A.-17 | B.-7 | C.-12 | D.12 |
根据题意得
ax5+bx3+cx-5=7,
∴当x=2时,ax5+bx3+cx=12,
∴-(ax5+bx3+cx)=-12,
即当x=-2时,ax5+bx3+cx=-12,
∴ax5+bx3+cx-5=-12-5=-17,
故选A.
ax5+bx3+cx-5=7,
∴当x=2时,ax5+bx3+cx=12,
∴-(ax5+bx3+cx)=-12,
即当x=-2时,ax5+bx3+cx=-12,
∴ax5+bx3+cx-5=-12-5=-17,
故选A.
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