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Solve for x: (9/25)^1−2⁢𝑥 = (125/27)^𝑥−2 - Mathematics

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Question

Solve for x:

`(9/25)^(1 - 2x) = (125/27)^(x - 2)`

Sum
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Solution

We need to solve:

`(9/25)^(1 - 2x) = (125/27)^(x - 2)`

Step 1: Prime factorization

  • `9 = 3^2, 25 = 5^2 ⇒ 9/25 = (3/5)^2`
  • `125 = 5^3, 27 = 3^3 ⇒ 125/27 = (5/3)^3`

So, `(9/25)^(1 - 2x) = (3/5)^(2(1 - 2x)`

`(125/27)^(x - 2) = (5/3)^(3(x - 2)`

Step 2: Rewrite bases

`(3/5)^(2(1 - 2x)) = (5/3)^(-2(1 - 2x))`

So equation becomes:

`(5/3)^(-2(1 - 2x)) = (5/3)^(3(x - 2))`

Step 3: Equating exponents

Since bases are equal:

`-2(1 - 2x) = 3(x - 2)`

Expand: `-2 + 4x = 3x - 6`

`4x - 3x = -6 + 2`

`x = -4`

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Chapter 6: Indices - MISCELLANEOUS EXERCISE [Page 69]

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B Nirmala Shastry Mathematics [English] Class 9 ICSE
Chapter 6 Indices
MISCELLANEOUS EXERCISE | Q 9. (i) | Page 69
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