The position vector of the point which divides the join of points 2→a−3→b and →a+→b in the raito 3 : 1, is
(a) 3→a−2→b2
(b) 7→a−8→b4
(c) 3→a4
(d) 5→a4
Let the position vector of the point R divides the join of points 2→a−3→b and →a+→b
∴ Position vector R =3(→a+→b)+1(2→a−3→b)3+1
Since, the position vector of a point R dividing the line segment joining the points P and Q, whose position vector of a point R dividing the line segment joining the points P and Q, whose positioin vectors are →p and →q in the ratio m : n internally , is given by m→q+n→pm+n
∴ R=5→a4