1.

If `a ,b ,c ,d`are in A.P. and `x , y , z`are in G.P., then show that `x^(b-c)doty^(c-a)dotz^(a-b)=1.`

Answer» Let `D` is the common difference in the given A.P.
Then,
`b-a = D, c-b = D, d-c = D`
`:. b-c = -D, c-a = 2D,a-b = -D`
As, `x,y and z` are in G.P.
`:. y^2 = zx`
Now, `x^(b-c)*y^(c-a)*z^(a-b) = x^(-D)*y^(2D)*z^(-D)`
`= (1/(zx))^D*(y^2)^D`
`=(y^2/(zx))^D`
`=((zx)/(zx))^D...[ `As ` y^2 = zx]`
`=1^D = 1`
`:. x^(b-c)*y^(c-a)*z^(a-b) = 1`


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