问题
选择题
当x=2时,多项式ax5+bx3+cx-5的值为2,当x=-2,这个多项式的值为( )
A.12
B.2
C.-2
D.-12
答案
将x=2代入代数式得:32a+8b+2c-5=2,即32a+8b+2c=7,
则当x=-2时,代数式=-32a-8b-2c-5=-(32a+8b+2c)-5=-7-5=-12.
故选D
当x=2时,多项式ax5+bx3+cx-5的值为2,当x=-2,这个多项式的值为( )
A.12
B.2
C.-2
D.-12
将x=2代入代数式得:32a+8b+2c-5=2,即32a+8b+2c=7,
则当x=-2时,代数式=-32a-8b-2c-5=-(32a+8b+2c)-5=-7-5=-12.
故选D