Arithmetic Sequences and Sums

The video tutorial explains how to find the sum of the first 28 terms of an arithmetic sequence using the formula S_n = n/2 * (A_1 + A_n). It demonstrates the process of identifying the first and 28th terms using the given sequence formula A_n = 23 - 4n. The tutorial concludes with calculating the sum, which is -980, and emphasizes that finding the common difference is unnecessary for this calculation.

What is the formula given for the arithmetic sequence in the problem?

• A sub n equals 23 plus 4n

• A sub n equals 23 minus 4n

• A sub n equals 23 times 4n

• A sub n equals 23 divided by 4n

What does S sub n represent in the context of the problem?

• The average of the first n terms of the sequence

• The common difference of the sequence

• The sum of the first n terms of the sequence

• The nth term of the sequence

How is the common difference of the sequence determined from the formula?

• By dividing each term by 4

• By multiplying each term by 4

• By subtracting 4 from each term

• By adding 4 to each term

What is the value of the first term, A sub 1, in the sequence?

• 19

• 31

• 27

• 23

What is the value of the 28th term, A sub 28, in the sequence?

• -85

• -89

• -93

• -97

Which of the following is NOT needed to find the sum of the first 28 terms?

• The first term

• The 28th term

• The number of terms

• The common difference

What is the sum of the first 28 terms of the sequence?

• -990

• -970

• -980

• -960

What operation is performed after finding the sum of the first and 28th terms to find the total sum?

• Divide by 2

• Multiply by 28

• Multiply by 14

• Add 28