# Inequality very hard

• Feb 25th 2013, 04:15 AM
leezangqe
Inequality very hard
Let $a,b,c,d\in \mathbb{R}$ and $\left\{\begin{matrix}
0 \frac{1}{a}+\frac{2}{b}+\frac{d}{c}\geq 3\\
\frac{2}{b}+\frac{d}{c}\geq 2
\end{matrix}\right.$
. Prove that:
$a^4+b^4+c^4-d^4\leq 17$
• Feb 25th 2013, 10:37 AM
Paze
Re: Inequality very hard
Unfortunately I can't help you with your problem, but I did fix your LaTex codes so that someone might have an easier time helping you. In the future, use '\\' (without the apostrophes) to create a line space. Pressing enter will produce these annoying BR tags :)

Let $a,b,c,d\in \mathbb{R}$ and $\left\{\begin{matrix}0. Prove that:
$a^4+b^4+c^4-d^4\leq 17$