1.

If `(a^n+b^n)/(a^(n-1)+b^(n-1))` is the GM between a and b, then the value of n is

Answer» We know that the AM between a and b is ` ((a +b))/2`
`((a^(n) + b^(n))/( a^(n-1) +b^(n-1)))` is the AM between a and b
` Rightarrow ((a ^(n) +b^(n))/ (a^(n-1) +b^(n -1)) = (a+b)/2`
` Rightarrow 2a^(n) +2b^(n) = a^(n) +a^(n-1) b+b^(n-1) a+b^(n)`
` Rightarrow a^(n) +b^(n) a^(n-1) b+b^(n-1) a`
` Rightarrow a^(n) -a^(n-1) b=b^(n-1) a-b^(n) `
` Rightarrow a^(n-1) (a-b) =b^(n-1) (a-b)`
` Rightarrow a^(n-1) =b^(n-1)`
` Rightarrow (a/b) ^(n-1) =1=(a/b)^(0) Rightarrow n-1 =0 Rightarrow n=1`
Hence, the required value of n is 1.


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