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Question -

If a(1/b + 1/c), b(1/c + 1/a), c(1/a + 1/b) are in AP., prove that a, b,c are in AP.



Answer -

Here, we know a(1/b +1/c), b(1/c + 1/a), c(1/a + 1/b) are in AP

Also, a(1/b + 1/c) +1, b(1/c + 1/a) + 1, c(1/a + 1/b) + 1 are in AP

Let us take LCM foreach expression then we get,

(ac+ab+bc)/bc ,(ab+bc+ac)/ac, (cb+ac+ab)/ab are in AP

1/bc, 1/ac, 1/ab arein AP

Let us multiplynumerator with ‘abc’, we get

abc/bc, abc/ac, abc/abare in AP

a, b, c are in AP.

Hence proved.

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