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Let f:N→Nf: \mathbb{N} \to \mathbb{N} defined by f(x)=3x2+2x+7f(x) = 3x^2 + 2x + 7, where N\mathbb{N} is set of natural numbers. Then f(x)f(x) is:

Solution

✅ Correct Option: 1

On N\mathbb{N} the function is strictly increasing, so distinct inputs give distinct outputs; it is injective.

The smallest value is f(1)=12f(1)=12, so values like 1, 2 and 7 are never attained; it is not surjective.

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