document.write( "Question 175215: How do I solve this problem? the first two terms of an arithmetic sequence are a(base1)=2 and a(base2)=4. what is the a(base10)? \n" ); document.write( "
Algebra.Com's Answer #130312 by gonzo(654)\"\" \"About 
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the formula for the nth term of a geometric sequence is:
\n" ); document.write( "---
\n" ); document.write( "\"a%5Bn%5D+=+a%5B1%5D%2Ar%5E%28n-1%29\"
\n" ); document.write( "---
\n" ); document.write( "you are given \"a%5B1%5D\" and \"a%5B2%5D\".
\n" ); document.write( "you use them to find r as follows:
\n" ); document.write( "\"a%5B2%5D+=+a%5B1%5D%2Ar%5E%282-1%29\" which becomes \"a%5B2%5D+=+a%5B1%5D%2Ar%5E1\"
\n" ); document.write( "substituting 4 for \"a%5B2%5D\" and 2 for \"a%5B1%5D\" you get:
\n" ); document.write( "4 = 2*r^1 = 2*r
\n" ); document.write( "solving for r, you get
\n" ); document.write( "r = 2
\n" ); document.write( "---
\n" ); document.write( "you now have r, and you can substitute in the general equation as follows:
\n" ); document.write( "\"a%5Bn%5D+=+a%5B1%5D%2Ar%5E%28n-1%29\"
\n" ); document.write( "substitute 2 for r, and 2 for \"a%5B1%5D\" and you get:
\n" ); document.write( "\"a%5Bn%5D+=+2%2A2%5E%2810-1%29\" = 2*2^9 = 2*512 = 1024.
\n" ); document.write( "---
\n" ); document.write( "the 10th term in the sequence is 1024.
\n" ); document.write( "you can test this by doing it the hard way (each term is done separately) as follows:
\n" ); document.write( "a(1) = 2
\n" ); document.write( "a(2) = 4
\n" ); document.write( "a(3) = 8
\n" ); document.write( "a(4) = 16
\n" ); document.write( "a(5) = 32
\n" ); document.write( "a(6) = 64
\n" ); document.write( "a(7) = 128
\n" ); document.write( "a(8) = 256
\n" ); document.write( "a(9) = 512
\n" ); document.write( "a(10) = 1024
\n" ); document.write( "---
\n" ); document.write( "each succeeding number is multiplied by the ratio.
\n" ); document.write( "you do that 9 times which is the same as multiplying the original number by 2^9.
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