Graph showing a scatter plot of data points P1, P2, P3, P4, ..., Pn. A line of best fit is drawn through the origin O(0,0). For each point Pi, a vertical dashed line is drawn to the line of best fit at point Mi. The points Pi and Mi are connected by a dashed line segment.
P1(a1,b1),P2(a2,b2),P3(a3,b3),…,Pn(an,bn) are a set of data points which are approximately linear through the origin O(0,0) .
To find the equation of the “line of best fit” through the origin, we minimise
(P1M1)2+(P2M2)2+(P3M3)2+⋯+(PnMn)2 where Mi lies on the line and has x -coordinate ai .
Find the gradient m of the “line of best fit” in terms of ai and bi , i=1,2,3,4,…,n .