多项式x3+ax2+bx+5被x-1除余7,被x+1除余9,则数对(a,b)=(  )A. (-2,3)B. (2,-3)C. (-3,2)D. (3,-2)

问题描述:

多项式x3+ax2+bx+5被x-1除余7,被x+1除余9,则数对(a,b)=(  )
A. (-2,3)
B. (2,-3)
C. (-3,2)
D. (3,-2)

多项式x3+ax2+bx+5被x-1除余7,即 x3+ax2+bx-2=(x-1)[x2+(a+1)x+(a+b+1)],即a+b+1=2,a+b=1 被x+1除余9,即 x3+ax2+bx-4=(x+1)[x2+(a-1)x+(b-a+1)],即b-a+1=-4,a-b=5,联立可得:a+b=1a−b=5,解得...
答案解析:由多项式x3+ax2+bx+5被x-1除余7,可得x3+ax2+bx-2=(x-1)[x2+(a+1)x+(a+b+1)],由多项式x3+ax2+bx+5被x+1除余9,可得x3+ax2+bx-4=(x+1)[x2+(a-1)x+(b-a+1)],于是可以得到a和b的二元一次方程组,解得a和b的值即可.
考试点:因式定理与综合除法.
知识点:本题主要考查因式定理与综合除法的知识点,解答本题的关键是熟练掌握整除带余的概念,此题难度不大.