If x = ∑ n = 0 ∞ a n ,   y = ∑ n = 0 ∞ b n ,   z = ∑ n = 0 ∞ c…

If x=n=0an, y=n=0bn, z=n=0cn, where a,b,c are in A.P. and a<1,b<1,c<1, abc0, then
  1. x,y,z are in A.P.
  2. x,y,z are in G.P.
  3. 1x,1y,1z are in A.P.
  4. 1x+1y+1z=1-a+b+c

Solution

x=1+a+a2=......

x=11-aa=1-1x

y=11-bb=1-1y

z=11-cc=1-1z

a,b,c are in A.P.

1-1x,1-1y,1-1z are in A.P.

-1x,-1y,-1z are in A.P.

1x,1y,1z are in A.P.

Asked in: JEE Main 2022 (27 Jun Shift 1)

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