Find the sum of the first 12 terms of the sequence. show all work for full credit. 1, -4, -9, -14, . . (2 points)

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Step-by-step explanation:

We are given the following arithmetic sequence and we are to find the sum of its first 12 terms:

1, -4, -9, -14, . . .

For that, we will use the formula for the sum of the arithmetic mean:

We know the value of the first term () but we need to find the value of . So we will use the following formula:

Substituting these values in the sum formula to get:

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