Răspuns:
[tex]\frac{1}{1*2} + \frac{1}{2*3} + ... + \frac{1}{2022*2023} =\\\\\frac{1}{1} - \frac{1}{2} + \frac{1}{2} - \frac{1}{3} + ... + \frac{1}{2022} - \frac{1}{2023} = \\\\1 - \frac{1}{2023} = \frac{2023-1}{2023} = \frac{2022}{2023}[/tex]
(√5-√4)(√3+√2)(√5+√4)(√2-√2) = (√5-√4)(√3+√2)(√5+√4)*0 = 0
Aia din mijloc nu știu cum se face