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Question

If $\frac{1}{x}=\frac{1}{p}+\frac{1}{q}$, then what is $\frac{pq}{p^2-q^2}\left(\frac{x+p}{x-p}-\frac{x+q}{x-q}\right)$ equal to ?

The correct answer is

2

To solve this problem, we need to manipulate the given equation to find the value of the expression:

Given:

\(\frac{1}{x} = \frac{1}{p} + \frac{1}{q}\)

First, find a common denominator on the right-hand side:

\(\frac{1}{x} = \frac{q + p}{pq}\)

This implies:

\(x = \frac{pq}{p + q}\)

Substitute \(x\) in the given expression:

\(\frac{pq}{p^2-q^2}\left(\frac{x+p}{x-p}-\frac{x+q}{x-q}\right)\)

This equals:

\(\frac{pq}{p^2-q^2}\left(\frac{\left(\frac{pq}{p+q}\right)+p}{\left(\frac{pq}{p+q}\right)-p}-\frac{\left(\frac{pq}{p+q}\right)+q}{\left(\frac{pq}{p+q}\right)-q}\right)\)

First handle the two fractions separately:

  • Let's simplify the first part: 
    \(\frac{\left(\frac{pq}{p+q}\right)+p}{\left(\frac{pq}{p+q}\right)-p} = \frac{\frac{pq + p(p + q)}{p+q}}{\frac{pq - p(p+q)}{p+q}}\)
  • Now simplify the second part: 
    \(\frac{\left(\frac{pq}{p+q}\right)+q}{\left(\frac{pq}{p+q}\right)-q} = \frac{\frac{pq + q(p + q)}{p+q}}{\frac{pq - q(p+q)}{p+q}}\)

Subtract these simplified terms:

\(-\frac{2pq + p^2}{p^2} + \frac{2pq + q^2}{q^2} = -1 +1\)

Finally, plug these back into the main expression:

\(\frac{pq}{p^2-q^2}\times 2 = 2\)

The correct answer is:

Option 2

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Important Questions from Algebra

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  2. If (10a 3+ 4b 3) : (11a 3- 15b 3) = 7 : 5, then (3a + 5b) : (9a - 2b) =?

  3. If 4sin 2 θ = 3(1+ cos θ), 0° < θ < 90°, then what is the value of (2tan θ + 4sin θ - sec θ)? 
  4. The value of:

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  5. If (x + y) 3+ 27(x - y) 3= (Ax - 2y)(Bx 2+ Cxy + 13y 2), then the value of A - B - C is:

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