# Algebra II quiz.

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##### Recall: in an arithmetic series, the difference "d" between any two adjacent terms is always the same.

1.) What can we say about the first term in an arithmetic series?

A.) It is always 1.

B.) It cannot be 4.

C.) It cannot be 10.

D.) It can be any number!

2.) An arithmetic series has t1=1, tn=11, n=11. What is its sum?

A.) Not enough information - what is d?

B.) 110

C.) 55

D.) 66

3.) An arithmetic series has t1=1, d=4, n=11. What is its sum?

A.) 40

B.) 440

C.) 231, since tn = 1+(10*4) = 41.

D.) Unknown, since we don't know tn.

4.) An arithmetic series has t1=1, tn=49, n=10. What is its sum?

A.) 500

B.) 250

C.) 275

D.) Unknown, since we don't know d.

5.) An arithmetic series has d=2, tn=50, n=10. What is its sum?

A.) 390

B.) 820

C.) 410, since t1=tn-9*2=50-18=32.

D.) Unknown, since we don't know t1.

6.) An arithmetic series has t1=32, d=2, tn=50. What is its sum?

A.) 390

B.) 820

C.) 410 (tn-t1=(n-1)*d->50-32=(n-1)*2->n=10)

D.) Unknown, since we don't know n.