skrócenie do nawiasu pryncpisal: https://cms.nowaera.pl/show/448839 66.1 1 sposob czy jest ktos w stanie wytlyumaczyc to skrócenie do (2𝑛 + 1+ 2𝑛 − 1)

mat: a_n+1−a_n= (−1)ⁿ⁺²(2n+1) −(−1)ⁿ⁺¹(2n−1)= (−1)ⁿ⁺²(2n+1)− (−1)ⁿ⁺²⁻¹(2n−1) = (−1)ⁿ⁺²[2n+1− (−1)⁻¹(2n−1)]= = (−1)ⁿ⁺²[2n+1 +2n−1]= (−1)ⁿ⁺²*4n