- #1
utkarshakash
Gold Member
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Homework Statement
If [itex]x_1,x_2,x_3...x_n[/itex] are in H.P. then prove that [itex]x_1x_2+x_2x_3+x_3x_4...+x_{n-1}x_n=(n-1)x_1x_n[/itex]
Homework Equations
The Attempt at a Solution
Since [itex]x_1,x_2,x_3...x_n[/itex] are in H.P. therefore
[itex] \frac{1}{x_1},\frac{1}{x_2},\frac{1}{x_3}...,\frac{1}{x_n}[/itex] will be in A.P. Now common difference of this A.P.
[itex]d=\dfrac{\frac{1}{x_n}-\frac{1}{x_1}}{n-1} \\
x_1x_n=\dfrac{x_1-x_n}{d(n-1)}\\
(n-1)x_1x_n=\dfrac{x_1-x_n}{d} [/itex]
Looks like I've arrived at the R.H.S. But what about LHS?