1) find a1 of an arithmetic sequence given that a5 = 45 and a17 = 129
2) The third term of a geometric sequence is 27. The common ratio is 3. Find the ninth term.
3)solve logx + log(x-3) = log108
4) Suppose the two spinners shown are each spun once. Find the probability that the first spinner lands on a number that is greater than 2 and the sum of the spinners is less than 8. (note: both spinners are divided into 4 pieces, 1-4)
Algebra 2 questions?? Easy 10 points?
2014-06-05 2:26 pm
回答 (1)
2014-06-05 2:32 pm
nth term is a + (n - 1)d....where a is a1 and d is the common difference.
so, 5th term => a + 4d = 45
and 17th term => a + 16d = 129
Subtracting the first equation from the second gives:
12d = 84
so, d = 7
Then, a + 4(7) = 45
i.e. a = 17...first term
:)>
so, 5th term => a + 4d = 45
and 17th term => a + 16d = 129
Subtracting the first equation from the second gives:
12d = 84
so, d = 7
Then, a + 4(7) = 45
i.e. a = 17...first term
:)>
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