ແກ້ a_{n}=(n+1)^2

$$a _ { n } = ( n + 1 ) ^ { 2 }$$

ແກ້ສຳລັບ a_n

$$a_{n}=\left(n+1\right)^{2}$$

ຂັ້ນຕອນການແກ້

ໃຊ້ທິດສະດີທະວິນາມ \left(a+b\right)^{2}=a^{2}+2ab+b^{2} ເພື່ອຂະຫຍາຍ \left(n+1\right)^{2}.

$$a_{n}=n^{2}+2n+1$$

ແກ້ສຳລັບ n

$$n=-\left(\sqrt{a_{n}}+1\right)$$

$$n=\sqrt{a_{n}}-1\text{, }a_{n}\geq 0$$