Question

Please look at picture! thank you!

Answer 1

16

Explanation:

write the equation for a3

a3 = a2 + 3(3) -> eq1

now find what is a2, write equation for a2

a2 = a1 + 3(2) -> eq2

you know a1=1, replace that into eq2

a2 = 1 + 3(2) = 1 + 6 = 7

replace a2 into eq1

a3 = 7 +3(3) = 7 + 9 = 16