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If p = 5 – 2 √6, then find the value of p2+1p2p^2+\frac{1}{p^2}p2+p21​​​
Question

If p = 5 – 2 √6, then find the value of p2+1p2p^2+\frac{1}{p^2}​​

A.

√6-√5

B.

25+√6

C.

98

D.

100

Correct option is C

Given:
p = 5 - 2 √6
Formula Used:
To find p2+1p2p^2 + \frac{1}{p^2}​, we can use the identity: p2+1p2=(p+1p)22p^2 + \frac{1}{p^2} = \left( p + \frac{1}{p} \right)^2 - 2 \\​​
Solution:
Given p=526,1p=15261p=(5+26)(526)(5+26)=5+262524=5+26p+1p=(526)+(5+26)=10p2+1p2=(p+1p)22p2+1p2=1022=1002=98Answer:p2+1p2=98\text{Given } p = 5 - 2 \sqrt{6}, \\\frac{1}{p} = \frac{1}{5 - 2 \sqrt{6}} \\\frac{1}{p} = \frac{ (5 + 2 \sqrt{6})}{(5 - 2 \sqrt{6})(5 + 2 \sqrt{6})} \\= \frac{5 + 2 \sqrt{6}}{25 - 24} = 5 + 2 \sqrt{6} \\p + \frac{1}{p} = (5 - 2 \sqrt{6}) + (5 + 2 \sqrt{6}) = 10 \\p^2 + \frac{1}{p^2} = \left( p + \frac{1}{p} \right)^2 - 2 \\p^2 + \frac{1}{p^2} = 10^2 - 2 = 100 - 2 = 98 \\\text{Answer:} \\p^2 + \frac{1}{p^2} = 98​​

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