×

# RMO

This problem appeared in the pre RMO test in my school How shall we solve this -

PROVE THAT

$$\frac{a^{2} +1}{b+c} +\frac{b^{2} +1}{a+c} +\frac{c^{2} +1}{b+a}$$ >3 OR =3

Note by Avn Bha
2 years, 8 months ago

Sort by:

Without loss of generality, Take a>b>c.

a^{2} + 1 > 2a - Similarly for all So I substitute 2a, 2b, 2c in the numerators The new sum acquired is lower than the original.

Now take 2 common and send it to the other side of the equation

This now reduces to Nesbitt's Inequality. Nesbitt's Inequality.

Proved.

[By the way even I am preparing for RMO, I think these inequalities are basic- -Nesbitt's Inequality -RMS>AM>GM>HM -Chebycheff Inequality -Rearrangement Inequality -Triangle Inequality ] · 2 years, 8 months ago

Nice reducing it to Nesbitt's Inequality. Staff · 2 years, 8 months ago