If $f$ is continuous and $3\geq f(x)\geq 1$ for all $ x\in [0,1]$, show that $$ 1 \leq \int_0^1f(x)dx\int_0^1\Bigg(\frac{1}{f(x)}\Bigg)dx \leq \frac{4}{3}. $$
Thanks!
If $f$ is continuous and $3\geq f(x)\geq 1$ for all $ x\in [0,1]$, show that $$ 1 \leq \int_0^1f(x)dx\int_0^1\Bigg(\frac{1}{f(x)}\Bigg)dx \leq \frac{4}{3}. $$
Thanks!
Copyright © 2021 JogjaFile Inc.
By C-S $$ \int\limits_0^1f(x)dx\int\limits_0^1\frac{1}{f(x)}dx \geq \left(\int\limits_0^11dx\right)^2=1.$$ For the proof of the right inequality use the Schweitzer's inequality.
See here:
http://www.ssmrmh.ro/wp-content/uploads/2016/08/INTEGRAL-FORMS-FOR-SCHWEITZERS-AND-POLYA-SZEGOS-INEQUALITIES.pdf