MathematicsHard202×since 2002Q5813Let a→\overrightarrow aa = i^\widehat ii + 2j^\widehat jj −-− 3k^\widehat kk and b→=2i^\overrightarrow b = 2\widehat ib=2i −-− 3j^\widehat jj + 5k^\widehat kk. If r→\overrightarrow rr ×\times× a→\overrightarrow aa = b→\overrightarrow bb ×\times× r→\overrightarrow rr, r→\overrightarrow rr . (αi^+2j^+k^)\left( {\alpha \widehat i + 2\widehat j + \widehat k} \right)(αi+2j+k) = 3 and r→ . (2i^+5j^−αk^)\overrightarrow r \,.\,\left( {2\widehat i + 5\widehat j - \alpha \widehat k} \right)r.(2i+5j−αk) = −-−1, α\alphaα ∈\in∈ R, then the value of α\alphaα + ∣r→∣2{\left| {\overrightarrow r } \right|^2}r2 is equal to :A13B11C9D15Check answerSkip