[tex]a_{n} = n^{2}-2n < 8 \ \ \wedge \ \ n \in N+\\\\n^{2}-2n -8 < 0\\\\\Delta = (-2)^{2}-4\cdot1\cdot(-8) = 4 + 32 = 36\\\\\sqrt{\Delta} = \sqrt{36} = 6\\\\n = \frac{-(-2)-6}{2} = -2 \ \ \vee \ \ n = \frac{-(-2)+6}{2} = 4\\\\n \in (-2;4) \ \ \wedge \ \ n \in N+\\\\n \in \{1,2,3\}[/tex]
Odp. Wyrazy: a₁, a₂, a₃ są mniejsze od 8.
