How to Prove This Complex Inequality Involving Absolute Values?

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SUMMARY

The discussion centers on proving the inequality |\frac{1}{2}(a+b)|^p \leq \frac{1}{2}(|a|^p+|b|^p for complex numbers a and b. A proposed approach involves manipulating the inequality using the expression |\frac{1}{2}(a+b)|^{p}\leq(\sqrt[p]{\frac{1}{2}}|(a+b)|)^{p}-pab. The conversation highlights that while this method may work for certain values of p, such as p=2, it raises questions about the validity of the inequality for p=1 due to the subtraction of the term ab on the right-hand side.

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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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