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Find a polynomial  of degree  such that both of these properties hold:

 f(x) is divisible by x^3.

 f(x)+2 is divisible by (x+1)^3.

Write your answer in expanded form (that is, do not factor f(x)).

 

One person gave me this answer: 

 

Since f(x) is divisible by x^3, f(x) is of the form ax^5 + bx^4 + cx^3.

 

You then want ax^5 + bx^4 + cx^3 + 2 to be divisible by (x + 1)^3.  Using long division, you get the equations

-10a  + 6b - 3c = 0

4a - 3b + 2c = 0

-a + b - c + 2 = 0

==> a = 6, b = 16, c = 12

 

So f(x) = 6x^5 + 16x^4 + 12x^3.

 

But it was incorrect. Could someone help me out ? ty! 

 Oct 26, 2021
 #1
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The polynomial is $8x^5 - 16x^4 + 12x^3$.

 Nov 7, 2021

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