CBSE 2026 · Region 4 · Set 1 · Q20 · 1 mark
Assertion (A): A function $\displaystyle \mathrm{f}: \mathrm{N} \rightarrow \mathrm{N}$ given by $\displaystyle \mathrm{f}(\mathrm{x})=\mathrm{x}^{3}+2, \forall \mathrm{x} \in \mathrm{N}$ is one-one but not onto.
Reason (R) : Since $\displaystyle \forall \mathrm{y} \in \mathrm{N}$ (Codomain), there does not exist $\displaystyle \mathrm{x}=(\mathrm{y}-2)^{1 / 3}$ in N (Domain) such that $\displaystyle \mathrm{f}(\mathrm{x})=\mathrm{x}^{3}+2=\mathrm{y}$.
Official answer
From CBSE’s own marking scheme for this paper.
(A)
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
Relations and FunctionsTypes of FunctionsUnderstandassertion_reasonmedium
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CBSE Class 12 Mathematics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.