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Exponents — Maths STD 7 — Question

Maharashtra BoardEnglish MediumSTD 7MathsExponents1 Mark
Question
$(25^2-15^2)^{\frac{3}{2}}=$
  1. 4000
  2. 8000
  3. 3125
  4. 1024
✓

Answer

  1. 8000
​​​​​​​Solution:

Since,

$(25^2-15^2)^{\frac{3}{2}}$

$=(625-225)^{\frac{3}{2}}$

$=(400)^{\frac{3}{2}}$

$=(20^2)^{\frac{3}{2}}$

$=20^{2\times\frac{3}{2}}$ $\Big[\text{As, }(\text{x}^{\text{m}})^{\text{n}}=\text{x}^{\text{mn}}\Big]$

$=20^3$

$=8000$

Hence, the correct alternative is option (b).

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