how can i do (a+b+c)(1/a + 1/b + 1/c)>= 9 is there any theorem to use? i dont know theorems based on this.. can u help me with this?
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Originally Posted by nh149 how can i do (a+b+c)(1/a + 1/b + 1/c)>= 9 is there any theorem to use? i dont know theorems based on this.. can u help me with this? Without conditions on a, b and c this question makes no sense
actually, we must just precise that a, b , c are three positif reals not null. indeed, we can apply the Cauchy-Schwarz's inegalitie: we have directly: cqfd @+
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