Wykaż że liczba  jest całkowita.

[latex]frac{log^24-log^225}{2(log2-log5)}=frac{(log4-log25)(log4+log25)}{2(log2-log5)}=frac{(log2^2-log5^2)cdot log(4cdot25)}{2(log2-log5)}\\=frac{(2log2-2log5)cdot log100}{2(log2-log5)}=frac{2(log2-log5)cdot log10^2}{2(log2-log5)}=log10^2=2log10=2\\====================================\Wzory:\\a^2-b^2=(a-b)(a+b)\\log_ab+log_ac=log_a(bcdot c)\\log_ab^c=ccdot log_ab\\log_aa=1[/latex]