AP EAMCET · Maths · Complex Number

Consider the following statements :
I : If \(a\) and \(b\) are positive real numbers, then \(\sqrt{-a} \times \sqrt{-b}=\sqrt{a b}\)
II : The argument of \(\frac{1+i \sqrt{3}}{1-i \sqrt{3}}\) is \(120^{\circ}\)
Then

A Only I is true
B Only II is true
C Both I and II are true
D Neither I nor II is true

Verified Solution

Answer & Solution

Correct Answer

(B) Only II is true

Step-by-step Solution

Detailed explanation

I: \(\sqrt{-a}\sqrt{-b} = (i\sqrt{a})(i\sqrt{b}) = i^2\sqrt{ab} = -\sqrt{ab}\). Statement I is false. II: Arg of \(\frac{1+i \sqrt{3}}{1-i \sqrt{3}}\)…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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Consider the following statements :I : If \(a\) and \(b\) are positive real numbers, then \(\sqrt{-a} \times \sqrt{-b}=\sqrt{a b}\)II : The argument of \(\frac{1+i \sqrt{3}}{1-i \sqrt{3}}\) is \(120^{\circ}\)Then

Step-by-step Solution

Consider the following statements :
I : If \(a\) and \(b\) are positive real numbers, then \(\sqrt{-a} \times \sqrt{-b}=\sqrt{a b}\)
II : The argument of \(\frac{1+i \sqrt{3}}{1-i \sqrt{3}}\) is \(120^{\circ}\)
Then