[tex]2^n+2^n+2^n+2^n=4 \cdot 2^n=2^2 \cdot 2^n=2^{n+1}[/tex]
Czyli :
[tex](\forall n \in N)(2^n+2^n+2^n+2^n=2^{n+2})[/tex]
[tex](2^n+2^n)^2=(2 \cdot 2^n)^2=2^2 \cdot 2^{2n}=4 \cdot 4^n[/tex]
Czyli :
[tex](\forall n \in N)((2^n+2^n)^2=4 \cdot 4^n)[/tex]
