Question

Find the $n^{\text{th}}$ term of sequence -3, 0, 5, ...

• A. 1 - 4n
• B. n - 2
• C. $n^2$ + 1
• D. $n^2$ - 4

Answer 1

The correct option is D $n^2$ - 4

$T_1$ = $1^2$ - 4 = 1 - 4 = -3 OR
= (1-2)$\times$(1+2) = (-1)$\times$3 = -3
$T_2$ = $2^2$ - 4 = 4 - 4 = 0 OR
= (2-2)$\times$(2+2) = 0$\times$4 = 0
$T_3$ = $3^2$ - 4 = 9 - 4 = 5 OR
= (3-2)$\times$(3+2) = 1$\times$5 = 5
thus
$T_n$ = $n^2$ - 4 OR
= (n-2)$\times$(n+2)
= $n^2$ + 2n - 2n - 4 = $n^2$ - 4