by nathi123 » Tue Mar 20, 2018 4:23 pm
Let's assume that [tex]\sqrt{2}=\frac{p}{q}[/tex] where p,q[tex]\in Z; (p,q)=1 \Rightarrow 2=\frac{p^{2}}{q^{2}}\Leftrightarrow p^{2}=2q^{2}; (p,q)=1\Rightarrow
p=2m;m\in Z[/tex]
[tex]\Rightarrow p^{2} = 4m^{2} \Rightarrow 4m^{2} = 2q^{2} \Leftrightarrow q^{2}=2m^{2} \Rightarrow q=2n; n\in Z \Rightarrow p=2m ; q=2n[/tex]
contradiction with (p,q)=1 [tex]\Rightarrow \sqrt{2}[/tex] is an irrational number.