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Exponents and Powers — MATHS STD 7 — Question

Gujarat BoardEnglish MediumSTD 7MATHSExponents and Powers1 Mark
MCQ
If $3^{\text{n}-2}=\frac{1}{81},\text{n}=$
  • A
    $0$
  • B
    $1$
  • C
    $2$
  • ✓
    $-2$
✓

Answer

Correct option: D.
$-2$
Given, $3^{\text{n}-2}=\frac{1}{81}$
$\Rightarrow3^{\text{n}-2}=\frac{1}{3^4}$
$\Rightarrow3^{\text{n}-2}=3^{-4}$
$\Rightarrow\text{n}-2=-4$
$\Rightarrow\text{n}=-2$

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