Let a and b be two vectors, Let |a|=1,|b|=4 and a b=2.

Question

Let $\vec{a}$ and $\vec{b}$ be two vectors, Let $|\vec{a}|=1,|\vec{b}|=4$ and $\vec{a}\cdot \vec{b}=2$. If $\vec{c}=(2\vec{a}	imes \vec{b})-3\vec{b}$, then the value of $\vec{b}\cdot \vec{c}$ is :

Accepted Answer

$\overset{	o }{b}.\overset{	o }{c}=\overset{	o }{b}.(2\vec{a}	imes \overset{	o }{b})-3\vec{b}.\overset{	o }{b}$

$=0-3|\vec{b}{|}^{2}=-48$

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