CBSE 2026 · Region 3 · Set 1 · Q15 · 1 mark
If $\displaystyle (\vec{\mathrm{a}}+\vec{\mathrm{b}}) \cdot(\vec{\mathrm{a}}-\vec{\mathrm{b}})=198$ and $\displaystyle |\vec{\mathrm{a}}|=10|\vec{\mathrm{b}}|$, then :
Official answer
From CBSE’s own marking scheme for this paper.
(B)
$\displaystyle |\overrightarrow{\mathrm{b}}|=\sqrt{2}$
Vector AlgebraProduct of Two VectorsApplymcqmedium
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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.