How to Prove This Complex Inequality Involving Absolute Values?

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The discussion revolves around proving the inequality |(1/2)(a+b)|^p ≤ (1/2)(|a|^p + |b|^p) for complex numbers a and b. A suggested approach involves manipulating the inequality by introducing terms that account for the complexity of the expression. However, concerns are raised about the validity of subtracting terms like pab, particularly when p is not equal to 2, which may lead to inaccuracies in the proof. The conversation highlights the challenges in handling absolute values and powers in inequalities. Ultimately, the need for a rigorous proof method remains a central focus.
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Need help with a complex inequality??

hey!
i been trying to do this inequality for a 2 hrs now and can't seem to prove it
|\frac{1}{2}(a+b)|^p \leq \frac{1}{2}(|a|^p+|b|^p) where a,b are complex numbers
Can anyone suggest a way??
thanks
 
Last edited:
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Try this:

|\frac{1}{2}(a+b)|^{p}\leq(\sqrt[p]{\frac{1}{2}}|(a+b)|)^{p}-pab

Yes, I know, the last term is only pab if p=2, but you will always be subtracting somthing at the end, no matter the value of p. I think this kinda works...
 
so you saying that |\frac{1}{2}(a+b)|^{p}\leq(\sqrt[p]{\frac{1}{2}}|(a+b)|)^{p}-pab \leq \frac{1}{2}(|a|^p+|b|^p)
 
for p = 1
|\frac{1}{2}(a+b)|\leq(\frac{1}{2}|(a+b)|)-ab
isnt this false because you subtracting a ab on the RHS?
 
Last edited:
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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