If A1and A2 be the two A. M. s between two numbers 7and 1/7 then (2A1-A2)(2A2-A1)=
49
48/7
50/7
1
Find the value of (2A1-A2)(2A2-A1):
Given 7,A1,A2,1/7 are in AP.
⇒A1-7=A2–A1⇒2A1–A2=7….....(i)andA2–A1=17–A2⇒2A2–A1=1/7...…(ii)
Multiply (i) and (ii). we get
(2A1–A2)(2A2–A1)=7×17=1
Hence, the correct option is (D).
If A1,A2 be two AM'x and G1,G2 be two GM's between a and b, then find the value of A1+A2G1G2