Find the explicit formula for the arithmetic sequence rn given below. Note that r1=13.13,10,7,4,1,…Select the correct answer below:rn=16−3nrn=10−3nrn=13−3nrn=10−4nrn=17−4nrn=13−4n

Solution
[tex]13,10,7,4,1,...[/tex][tex]\begin{gathered} r_1=13 \\ d=r_2-r_1 \\ d=10-13 \\ d=-3 \end{gathered}[/tex]Standard formula
[tex]r_n=r_1+(n-1)d[/tex]Now substitute
[tex]\begin{gathered} r_n=13+(n-1)-3 \\ r_n=13-3n\text{ +3} \\ r_n=16-3n \end{gathered}[/tex]The final answer
Option A