MCQ 2011 Mark
The value of $\Big(\frac{2}{5}\Big)^{-2}$ is:
- A$\frac{4}{5}$
- B$\frac{4}{25}$
- ✓$\frac{25}{4}$
- D$\frac{5}{2}$
Answer
View full question & answer→Correct option: C.
$\frac{25}{4}$
Using law of exponents, $\text{a}^{-\text{m}}=\frac{1}{\text{a}^\text{m}} [\because$ a is non$-$integer$]$
$\therefore \Big(\frac{2}{5}\Big)^{-2}=\frac{1}{\Big(\frac{2}{5}\Big)^{2}}$
$=\frac{1}{\frac{4}{25}}$
$=\frac{25}{4}$
$\therefore \Big(\frac{2}{5}\Big)^{-2}=\frac{1}{\Big(\frac{2}{5}\Big)^{2}}$
$=\frac{1}{\frac{4}{25}}$
$=\frac{25}{4}$