# Precalculus Examples

, , , ,
Step 1
This is the formula to find the sum of the first terms of the sequence. To evaluate it, the values of the first and th terms must be found.
Step 2
This is an arithmetic sequence since there is a common difference between each term. In this case, adding to the previous term in the sequence gives the next term. In other words, .
Arithmetic Sequence:
Step 3
This is the formula of an arithmetic sequence.
Step 4
Substitute in the values of and .
Step 5
Simplify each term.
Apply the distributive property.
Multiply by .
Step 6
Subtract from .
Step 7
Substitute in the value of to find the th term.
Step 8
Multiply by .
Step 9
Subtract from .
Step 10
Replace the variables with the known values to find .
Step 11