1.

If the product of the roots of the equation `x^(2) - 2sqrt(2) kx + 2e^(2 log k) -1 = 0` is 31, then the roots of the equation are real for k equal toA. 1B. 2C. 3D. 4

Answer» Correct Answer - D
It is given that the product of roots is 31
`therefore" "2e^(2 log k) -1 = 31`
`rArr" "2k^(2) - 1 = 31 rArr 2k^(2) = 32 rArr k^(2) = 16 rArr k = +- 4`
But, log k is defined for `k gt 0`. Therefore, k = 4
We have, Disc `= 8k^(2) - 8 e^(2 log k) + 4 = 8k^(2) - 8k^(2) + 4 = 4 gt 0` for all k.
Hence, k = 4.


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