A geometric sequence is a sequence of numbers where each term after the first is found by multiplying the previous term by a constant called the common ratio. In this case, the first term (a) is 4 and the common ratio (r) is 5.
The first three terms can be calculated as follows:
First term: a = 4
Second term: a × r = 4 × 5 = 20
Third term: 20 × r = 20 × 5 = 100
So, the first three terms of the geometric sequence are 4, 20, and 100.