SOLUTION: Find the first term and the common difference of an arithmetic sequence if its 5th term is 33 and the 20th is 123

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Question 1084810: Find the first term and the common difference of an arithmetic sequence if its 5th term is 33 and the 20th is 123
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
a%5Bn%5D=a%5B1%5D%2B%28n-1%29d

its 5th term is 33
a%5B5%5D=a%5B1%5D%2B%285-1%29d
33=a%5B1%5D%2B4d

the 20th term is 123
a%5B20%5D=a%5B1%5D%2B%2820-1%29d
123=a%5B1%5D%2B19d

Solve the system:

system%28a%5B1%5D%2B4d=33%2Ca%5B1%5D%2B19d=123%29

a1 will be the first term and d will be
the common difference.  You finish.

Edwin