Answer:
Let's use the formula for the sum of the first n terms of an arithmetic sequence to find the value of the common difference d:
S = n/2 * (2a1 + (n-1)d), where S is the sum of the first n terms, a1 is the first term, and d is the common difference.
We know that S = 1830 and n = 30, so we can write:
1830 = 30/2 * (2a1 + 29d)
1830 = 15(2a1 + 29d)
122 = 2a1 + 29d
Next, we know that the 8th term is 31, so we can write:
a8 = a1 + 7d = 31
Now we have two equations with two unknowns, so we can solve for a1 and d:
122 = 2a1 + 29d
31 = a1 + 7d
Multiplying the second equation by 2 and subtracting it from the first equation, we get:
60 = 15d
So d = 4.
Substituting d = 4 into the equation a1 + 7d = 31, we get:
a1 + 28 = 31
a1 = 3
Therefore, the first three terms of the arithmetic sequence are:
a1 = 3
a2 = a1 + d = 3 + 4 = 7
a3 = a2 + d = 7 + 4 = 11
So the first three terms are 3, 7, 11.