50² = (25*2)² = 25²*2² = (5²)² *4 = [tex]5^{4}[/tex] * 4[tex]5^{4}[/tex] * 4 = [tex]5^{4}[/tex] * (5-1) = [tex]5^{5}[/tex] - [tex]5^{4}[/tex]
