If $\vec a, \vec b$ are the position vectors of A, B respectively and C is a point on AB produced such that AC = 3 AB, then the position vector of C is
Answer & explanation
Correct answer: option 2
Let the position vector for C be $\vec c$
Clearly, B divides AC internally in the ratio 1 : 2.
$∴\vec b=\frac{2\vec a+1.\vec c}{2+1}⇒\vec c=3\vec b-2\vec a$