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Consider the equation \({x}^{2}+4x-n=0\), where \(\mathrm{n}\in [20,100]\) is a natural number. Then the number of all d…

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Consider the equation \({x}^{2}+4x-n=0\), where \(\mathrm{n}\in [20,100]\) is a natural number. Then the number of all distinct values of n, for which the given equation has integral roots, is equal to

[JEE Main 2025, 4 Apr (Shift 1)]

a

\(7\)

b

\(8\)

c

\(6\)

d

\(5\)

✓ Correct answer: c)

\(6\)

Explanation

x² + 4x + 4 = n + 4
(x + 2)² = n + 4
x = -2 ± √n + 4
∵ 20 ≤ n ≤ 100
√24 ≤ √n + 4 ≤ √104
⇒ √n + 4 ∈ {5,6,7,8,9,10}
∴ '6' integral values of 'n' are possible

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