Question

已知多项式ax的5次方+bx的3次方+cx+9,当时x=—1,多项式的值为17.

Answer 1

x=-1

则ax^5+bx^3+cx+9

=a*(-1)^5+b*(-1)^3+c*(-1)+9

=-a-b-c+9

=-(a+b+c)+9

=17

所以a+b+c=-8

x=1

ax^5+bx^3+cx+9

=a*1^5+b*1^3+c*1+9

=(a+b+c)+9

=-8+9

=1