Hi there! :)
Answer:
5n + 6 = -3n - 10
Solve for n:
Add 3n to both sides:
5n + 3n + 6 = -3n + 3n - 10
8n + 6 = -10
Subtract 6 from both sides:
8n + 6 - 6 = -10 - 6
8n = -16
Divide both sides by 8:
8n/8 = -16/8
n = -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
Florence is closer to finishing the race