Mathematics · 2014
JEE Main · 11 April 2014, Shift 1 · Q85
If | c |^2=60 and c ×( i +2 j +5 k )= 0, then a value of c ·(-7 i +2 j +3 k ) is:
If $\displaystyle |\overrightarrow{\mathrm{c}}|^2=60$ and $\displaystyle \overrightarrow{\mathrm{c}} \times(\hat{i}+2 \hat{j}+5 \hat{k})=\overrightarrow{0}$, then a value of $\displaystyle \vec{c} \cdot(-7 \hat{i}+2 \hat{j}+3 \hat{k})$ is :
Official answer
(4)
$\displaystyle 12 \sqrt{2}$
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JEE Main 2014 Mathematics question, with the answer from NTA’s final answer key. Where our answers come from.