Question

12, 42, 72, 102..... Recursive Formula an = 12 * 30n-1 an = an-1 -12 an = 12 + 30 (n - 1 )an = an-1 + 12

Answer 1

Observe that the difference of the sequence is 30. The first term is 12.

Let's use the arithmetic sequence formula

$a_n=a_1+(n-1)d$

Replacing the given information, we have.

$\begin{gathered} a_n=12+(n-1)\cdot30 \\ a_n=12+30n-30 \\ a_n=30n-18 \end{gathered}$

Hence, the right answer is C because it relates correctly the first term and the difference.