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JEE MainMathematicsEasySets

Number of elements in set
A={p:p=(2n5+3n4+4n3+5n2+6)(n+2)n2+2n;n,p∈Z+}A = \left\{ p:p = \frac{\left( 2n^{5} + 3n^{4} + 4n^{3} + 5n^{2} + 6 \right)(n + 2)}{n^{2} + 2n};n,p \in Z^{+} \right\}
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P=(2n5+3n4+4n3+5n2+6)×(n+2)n2+2nP = \frac{\left( 2n^{5} + 3n^{4} + 4n^{3} + 5n^{2} + 6 \right) \times (n + 2)}{n^{2} + 2n}
⇒P=2n4+3n3+4n2+5n+6n\Rightarrow P = 2n^{4} + 3n^{3} + 4n^{2} + 5n + \frac{6}{n}
∵P∈z+\because P \in z^{+}.
6n∈z+⇒n\frac{6}{n} \in z^{+} \Rightarrow n is a factor of 6
⇒n=1,2,3,6\Rightarrow n = 1,2,3,6

Source: Grass-G / M-05 Mathematics Paper 10 October.docx

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