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← JEE Main 2022 · 27 Jul · Shift 1
MathematicsSingle correct+4 / -1Question 2 of 90

JEE Main 2022 · 27 Jul · Shift 1, Mathematics question 2

Let f,g:N−{1}→Nf,g:\mathbf N-\{1\}\to\mathbf N be functions defined by f(a)=αf(a)=\alpha, where α\alpha is the maximum of the powers of those primes pp such that pαp^\alpha divides aa, and g(a)=a+1g(a)=a+1, for all a∈N−{1}a\in\mathbf N-\{1\}. Then, the function f+gf+g is

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Answer and worked solution

Official answer: D

Not one-one. (f+g)(4)=2+5=7(f+g)(4)=2+5=7 and (f+g)(5)=1+6=7(f+g)(5)=1+6=7.

Not onto. The least value is (f+g)(2)=1+3=4(f+g)(2)=1+3=4, so 1, 2, 3 are never reached.

(D)