![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
Chứng minh rằng:
a, [tex]a^{2} + b^{2} - 2ab \geq 0[/tex]
b, [tex]\frac{a^{2} + b^{2}}{2} \geq ab[/tex]
c, a(a + 2) < [tex](a + 1)^{2}[/tex]
d, [tex]m^{2}+ n^{2} + 2 \geq 2(m + n)[/tex]
e, (a + b)[tex](\frac{1}{a} + \frac{1}{b})[/tex] [tex]\geq 4[/tex] (với a>0, b>0)
a, [tex]a^{2} + b^{2} - 2ab \geq 0[/tex]
b, [tex]\frac{a^{2} + b^{2}}{2} \geq ab[/tex]
c, a(a + 2) < [tex](a + 1)^{2}[/tex]
d, [tex]m^{2}+ n^{2} + 2 \geq 2(m + n)[/tex]
e, (a + b)[tex](\frac{1}{a} + \frac{1}{b})[/tex] [tex]\geq 4[/tex] (với a>0, b>0)