If a, b, c be the pth, qth and rth terms respectively of a HP, show that the points (bc, p), (ca, q) and (ab, r) are collinear.

Show that the points P(-2, 3, 5), Q(1, 2, 3) and R(7, 0, -1) are collinear.

Show that points A(a,b+c),B(b,c+a) and C(c,a+b) are collinear

Show that the points A(1, 2, 7), B(2, 6, 3) and C(3, 10, -1) are collinear.

Prove that the points (a, b), (c, d) and (a-c, b-d) are collinear, if ad = bc.

Show that the points A(1,3,2),B(-2,0,1) and C(4,6,3) are collinear.

Show that the point P(a, b + c), Q(b, c +a) and R(c, a + b) are collinear.

Show that the point A(1, -1, 3), B(2, -4, 5) and C(5, -13, 11) are collinear.

Show that the points A(2, 3, -4), B(1, - 2, 3) and C(3, 8, - 11) are collinear.

Prove by using distance formula that the points P(1, 2, 3), Q(-1, -1, -1) and R(3, 5, 7) are collinear.

If the position vectors of the points A,B and C be a,b and 3a-2b respectively, then prove that the points A,B and C are collinear.