Mathematics

Problem

15. Find the position vector of a point

R

which divides the line joining two points

P

and Q whose position vectors are

\hat{i}+2 \hat{j}-\hat{k}

and

-\hat{i}+\hat{j}+\hat{k}

respectively, in the ratio 2 : 1 (i) internally (ii) externally (i) internally (ii) externally