CA Foundation P3 · Chapter 1 · Question 6 of 9
If 3ˣ = 5ʸ = 15ᶻ, then z equals:
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: B) xy/(x + y)
Explanation
Let 3ˣ = 5ʸ = 15ᶻ = k. Then 3 = k^(1/x), 5 = k^(1/y) and 15 = k^(1/z). Since 15 = 3 x 5, k^(1/z) = k^(1/x + 1/y), so 1/z = 1/x + 1/y = (x + y)/xy. Therefore z = xy/(x + y).