In: Math
If a, b, c are in A.P. and P is the A.M. between a and b, and q is the A.M. between b and c, show that b is the A.M. between p and q.
Since a,b,c are in AP
2b=a+c—(i)
P is the AM between a and b
⇒P= a+b / 2
2P= a+b —(ii)
Similarly q is the A.M. between b and c
2Q=b+c —-(iii)
On adding equations (ii) and (iii) we get
2P+ 2Q=b+c + a+b
2(P+Q)= b+ (a+c)
2(P+Q)= 2b
2(P+Q)= 4b
(P+Q) / 2= b
b is the A.M of P & Q.