Question

Resolva a equação $\left \ ({{n-1} \atop {2}}) \right.= \left \ ({{n+1} \atop {4}}) \right.$ com n ≥3.

Answer 1

(n - 1)  = (n + 1)     multiplica em cruz
(   2  )     (   4   )

4.(n - 1) = 2.(n + 1)
4n - 4 = 2n + 2
4n - 2n = 2 + 4
2n = 6
n = 6/2
n = 3