ABC26GN2032 · Logarithms

Subject: General Aptitude · Chapter: Logarithms · Exam: · Marks: · Difficulty:

The value of $\log _{(-1 / 3)} 81$ is equal to
(a)- 27
(b)- 4
(c)4
(d)27
Answer
Answer (as printed): B
Explanation
Let $\log _{(-1 / 3)} 81=x$. Then, $\left(-\frac{1}{3}\right)^{x}=81=3^{4}=\left(-3^{4}\right)=\left(-\frac{1}{3}\right)^{4}$ $\therefore x=-4$ i.e., $\log _{(-1 / 3)} 81=-4$.

Explanation as extracted from the printed page; notation may be imperfect.

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