Question

2, 5, 25/2 ​ ,... Find the 9th term.

Answer 1

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