CA Foundation · Quantitative Aptitude · Sets, Relations and Functions, Limits and Continuity
Let f(x) = 2x + 3 and g(x) = x². What is the value of (g∘f)(2), that is g(f(2))?
For g∘f, apply f first and then g. Here f(2) = 2×2 + 3 = 7, and g(7) = 49. The answer is 49. Reversing the order gives f(g(2)) = 11, which is a different composite function and is incorrect here.
- A11
- B28
- C49Correct
- D53
Explanation
First compute the inner function: f(2) = 2(2) + 3 = 7. Then apply g: g(7) = 7² = 49. The value 11 comes from the wrong order, f(g(2)) = f(4) = 2(4) + 3 = 11.
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