Question
Question: If the roots of the quadratic equation x<sup>2</sup> – 4x – log<sub>3</sub>a = 0 are real, then the ...
If the roots of the quadratic equation x2 – 4x – log3a = 0 are real, then the least value of a is –
A
81
B
1/81
C
1/64
D
None of these
Answer
1/81
Explanation
Solution
Since the roots of the given equation are real.
\ Disc > 0 Ž 16 + 4 log3 a ³ 0
Ž log3 a ³ –4 Ž a ³ 3–4 Ž a ³ 1/81.
Hence, the least value of a is 1/81.