Step-by-step explanation:
seems to be multiplication, because the differences between the numbers change.
so, let's find the factor.
2 × f = 5
f = 5/2
5 × f = 5 × 5/2 = 25/2
ok, the factor 5/2 is confirmed.
a1 = 2
a2 = a1 × 5/2 = 2 × 5/2 = 10/2 = 5
a3 = a2 × 5/2 = a1 × 5/2 × 5/2 = 2 × 5/2 × 5/2 = 25/2
an = an-1 × 5/2 = a1 × (5/2)^(n-1) = 2 × (5/2)^(n-1)
a9 = 2 × (5/2)⁸ = 2 × 390,625/256 =
= 390,625/128 = 3,051.7578125
