Difference between revisions of "1950 AHSME Problems/Problem 20"

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== Problem==
 
== Problem==
  
When <math>x^{13}-1</math> is divided by <math>x-1</math>, the remainder is:
+
When <math>x^{13}+1</math> is divided by <math>x-1</math>, the remainder is:
  
 
<math> \textbf{(A)}\ 1\qquad\textbf{(B)}\ -1\qquad\textbf{(C)}\ 0\qquad\textbf{(D)}\ 2\qquad\textbf{(E)}\ \text{None of these answers} </math>
 
<math> \textbf{(A)}\ 1\qquad\textbf{(B)}\ -1\qquad\textbf{(C)}\ 0\qquad\textbf{(D)}\ 2\qquad\textbf{(E)}\ \text{None of these answers} </math>

Revision as of 17:50, 11 June 2013

Problem

When $x^{13}+1$ is divided by $x-1$, the remainder is:

$\textbf{(A)}\ 1\qquad\textbf{(B)}\ -1\qquad\textbf{(C)}\ 0\qquad\textbf{(D)}\ 2\qquad\textbf{(E)}\ \text{None of these answers}$

Solution

Solution 1

Use synthetic division. Notice that no matter what the degree of $x$ of the dividend is, the remainder is always $\boxed{\mathrm{(C)}\ 0.}$

Solution 2

Notice that $1$ is a zero of $x^{13} - 1$. By the factor theorem, since $1$ is a zero, then $x-1$ is a factor of $x^{13} - 1$, and when something is divided by a factor, the remainder is $\textbf{(C)}0$

See Also

1950 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 19
Followed by
Problem 21
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All AHSME Problems and Solutions