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Question: Answered & Verified by Expert
The remainder of $n^4-2 n^3-n^2+2 n-26$ when divided by 24 , is
MathematicsQuadratic EquationTS EAMCETTS EAMCET 2015
Options:
  • A 20
  • B 21
  • C 22
  • D 23
Solution:
1639 Upvotes Verified Answer
The correct answer is: 22
Let $\begin{aligned} f(n) & =n^4-2 n^3-n^2+2 n-26 \\ & =n^3(n-2)-n(n-2)-26 \\ & =(n-2)\left(n^3-n\right)-26 \\ & =(n-2) n\left(n^2-1\right)-26 \\ & =(n-2)(n-1) n(n+1)-26\end{aligned}$
$$
=24 k-48+22
$$
$[\because$ product of four consecutive natural numbers is divisible by 24]
$$
=24[k-2]+22
$$
Hence, remainder is 22.

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