If P² is proportional to R and Q² is proportional to R, (P ≠ Q), then which of the following are correct? 1. P² + Q² varies with R. 2. PQ varies with R. 3. P² - Q² varies with R. Select the correct answer using the code given below:
A.1 and 2 only
B.2 and 3 only
C.1 and 3 only
D.1, 2 and 3✓ Correct
Explanation
P² = aR and Q² = bR. Then P² + Q² = (a+b)R varies with R ✓. P² - Q² = (a-b)R varies with R ✓. PQ = √(P²Q²) = √(abR²) = R√(ab), so PQ varies with R ✓. All three statements are correct.
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