Question

Find the ninth term of the sequence sqrt 5, sqrt 10, ^2sqrt 5

sqrt 20
20 sqrt 5
16 sqrt 5
48 sqrt 5

Answer 1

`16√(5)` or C

Explanation:

Answer 2

the rule of geometric sequence is ⇒⇒⇒ a * r^(n-1)
Where a is the first term and r is the common ratio
for the given sequence √5 , √10 , 2√5 , .......
a = √5
r = √10 / √5 = √2
The ninth term = √5 * (√2)^(9-1) = √5 * (√2)⁸ = 16 √5

the correct answer is the third option 16√5