1.

Consider the equation `x^(2) + 2x - n = 0`m where `n in N` and `n in [5, 100]`. The total number of different values of n so that the given equation has integral roots isA. 8B. 3C. 6D. 4

Answer» Correct Answer - 1
`x^(2) + 2x - n = 0 rArr (x + 1)^(2) = n + 1`
`rArr x = -1 pm sqrt(n + 1)`
Thus, n + 1 should be a perfect square. Now,
`n in [5, 100] rArr n + 1 in [6, 101]`
Perfect square values of n + 1 are 9, 16, 25, 36, 49, 64, 81, 100.
Hence, number of values is 8.


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