If $Q$ denotes the set of all rational numbers and $f\left(\frac{p}{q}\right)=\sqrt{p^2-q^2}$ for any…

If $Q$ denotes the set of all rational numbers and $f\left(\frac{p}{q}\right)=\sqrt{p^2-q^2}$ for any $\frac{p}{q} \in Q$, then observe the following statements. I. $f\left(\frac{p}{q}\right)$ is real for each $\frac{p}{q} \in Q$ II. $f\left(\frac{p}{q}\right)$ is a complex number for each $\frac{p}{q} \in Q$. Which of the following is correct?
  1. Both I and II are true
  2. I is true, II is false
  3. I is false, II is true
  4. Both I and II are false

Solution

Given, $f\left(\frac{p}{q}\right)=\sqrt{p^2-q^2}$, for $\frac{p}{q} \in Q$ If $p < q$, then $f\left(\frac{p}{q}\right)$ is not real.

Asked in: AP EAMCET 2007

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