document.write( "Question 1167120: I am given the first three and the last term for this sequence. I need to know the number of terms for this?
\n" ); document.write( "1-k, 1+k, 1+3k..., 1+19k \n" ); document.write( "

Algebra.Com's Answer #791703 by math_helper(2461) $\"\"$ $\"About$

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\n" ); document.write( "1: 1-k
\n" ); document.write( "2: 1+k (2k was added to term 1)
\n" ); document.write( "3: 1+3k (2k was added to term 2)
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\n" ); document.write( "Now looking at this, you can say the n'th term will be (1-k) + 2(n-1)k
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\n" ); document.write( "As a check, look at term 3 above, we can plug in n=3: (1-k) + 2(3-1)k = (1-k) + 4k = 1+3k
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document.write( "Setting 1+19k = (1-k)+2(n-1)k and re-writing:\r\n" );
document.write( "        1+19k = 1-3k+2nk   \r\n" );
document.write( "          19k = -3k+2nk      << subtracted 1 from both sides\r\n" );
document.write( "          19  = -3+2n        << divided both sides by k\r\n" );
document.write( "          22  = 2n           << added 3 to both sides\r\n" );
document.write( "          11  = n            << divided both sides by 2\r\n" );
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\n" ); document.write( "n = 11, and n=1 is the first term, so there are 11 terms in the sequence.\r
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