Expressing the sum using sum notation of a geometric series

What is the purpose of using summation notation in a geometric series?

• To find the common difference

• To express the sum of the series

• To determine the first term

• To calculate the average of the series

How do you determine if a series is geometric?

• By checking if the terms are increasing

• By finding a common ratio between terms

• By ensuring all terms are even

• By calculating the sum of the first two terms

What is the formula for the nth term in a geometric series?

• a_n = a_1 * n^r

• a_n = a_1 / r^(n-1)

• a_n = a_1 * r^(n-1)

• a_n = a_1 + (n-1)d

If the common ratio is 3 and the first term is 5, what is the 3rd term in the series?

• 5

• 15

• 45

• 135

How do you determine the number of terms needed to reach a sum of 3645 in the series?

• By multiplying the first term by the common ratio

• By adding the terms until the sum exceeds 3645

• By finding the power of the common ratio that results in 3645

• By dividing 3645 by the first term