1.
[tex]a_{n} = (n-3)(n+2)\\\\a_{n} = 0\\\\(n-3)(n+2) = 0\\\\n \in N+\\\\n-3 = 0 \ \vee \ n+2 = 0\\\\n = 3 \ \vee \ n = -2 \ \notin D\\\\n = 3\\\\\underline{a_3 = 0}[/tex]
2.
[tex]a_{n} = 4n^{2}-2n\\\\a_{n} = 0\\\\4n^{2}-2n = 0 \ \ /:2\\\\2n^{2}-n = 0\\\\n(2n-1) = 0\\\\n\in N+\\\\n = 0 \ \vee \ 2n-1 = 0\\\\n=0 \ \notin D \ \vee \ n = \frac{1}{2} \ \notin D[/tex]
Odp. Żaden wyraz tego ciągu nie jest równy 0.
c)
[tex]a_{n} =n^{2}-4n+4\\\\a_{n} = 0\\\\n^{2}-4n+4 = 0\\\\(n-2)^{2} = 0\\\\n-2 = 0\\\\n = 2\\\\\underline{a_{2} = 0}[/tex]
