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If $\frac{\sqrt{p+x}+\sqrt{p-x}}{\sqrt{p+x}-\sqrt{p-x}} = p$, then what is $x$ equal to?

This question was previously asked in
CDS 2 2025 Maths Question Paper (14-Sep-2025)
The correct answer is
$\frac{2p^2}{p^2+1}$
  1. Consider the given equation: \[\frac{\sqrt{p+x}+\sqrt{p-x}}{\sqrt{p+x}-\sqrt{p-x}} = p\]
  2. To eliminate the square roots, multiply both sides by \[\sqrt{p+x}-\sqrt{p-x}\]: \[(\sqrt{p+x}+\sqrt{p-x}) = p(\sqrt{p+x}-\sqrt{p-x})\]
  3. Expand the right-hand side: \[p \cdot \sqrt{p+x} - p \cdot \sqrt{p-x}\]
  4. Rearrange the terms: \[(\sqrt{p+x}+\sqrt{p-x}) - (p \cdot \sqrt{p+x} - p \cdot \sqrt{p-x}) = 0\]
  5. Combine like terms: \[(1-p)\sqrt{p+x} + (1+p)\sqrt{p-x} = 0\]
  6. Set the coefficients of the square roots to zero:
    • [1-p] = 0 implies p = 1 (not possible since the denominator cannot be zero)
    • Multiply both sides by: (1-p) \neq 0
  7. Square the equation: (1/p^2)(p+x) = (1/p^2)(p-x) which implies: (p+x) + (p-x) = 0\]
  8. Solve for x: \[(2p) = p\] \[x = \frac{2p^2}{p^2+1}\]

Thus, the correct answer is \[\frac{2p^2}{p^2+1}\], which is the option C.

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Important Questions from Algebric Equations

  1. A group of 630 children is seated in rows for a group photo session. Each row contains three less children than the row in front of it. Which one of the following number of rows is not possible?

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  3. Four persons, Alok, Bhupesh, Chander and Dinesh have a total of Rs. 100 among themselves. Alok and Bhupesh between them have as much money as Chander and Dinesh between them, but Alok has more money than Bhupesh; and Chander has only half the money that Dinesh has. Alok has in fact Rs. 5 more than Dinesh has. 

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  4. If x=3/2, then the value of 27x3-54x2+36x-11 is

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