Which of the following CANNOT be a root of a polynomial in x of the form 9x^5+ax^3+b,where a and b a

题目

Which of the following CANNOT be a root of a polynomial in x of the form 9x^5+ax^3+b,where a and b are integers?
(a)-9 (b) -5 (c)1/4 (d)1/3 (e)9

答案

把root代入原公式会得到0,所以如果9(-9)^5+a(-9)^3+b9(-5)^5+a(-5)^3+b9(1/4)^5+a(1/4)^3+b9(1/3)^5+a(1/3)^3+b9(9)^5+a(9)^3+b当中的一个式子结果不是0的话,那么这个数字就不是这个polynomial的root.注意因为a和b是...