15. The pth, qth and rth terms of an A.P. are a, b, c, respectively. Show that
Given: The pth, qth and rth terms of an A.P. are a, b, c, respectively.
To prove :
Let the first term of AP be 't' and common difference be d
Subtracting equation 2 from 1, we get
Subtracting equation 3 from 2, we get
Equating values of d, from equation 4 and 5, we have
Hence proved.