Calculate the sum of the first four terms of a geometric progression, the first term of which is b1 = 2

Calculate the sum of the first four terms of a geometric progression, the first term of which is b1 = 2, and the denominator is q = 3.

Step one.

Let us determine what value will be equal to the second term of the desired geometric progression under the given conditions:

b2 = 2 * 3 = 6.

Step two.

Let us determine what value will be equal to the third term of the sought geometric progression under the given conditions:

b3 = 6 * 3 = 18.

Step three.

Let us determine what value will be equal to the fourth term of the required geometric progression under the given conditions:

b4 = 18 * 3 = 54.

Step four.

Then their sum is equal to:

2 + 18 + 6 + 54 = 80.

Answer: 80.