document.write( "Question 567832: the 15th term in an arithmetic sequence is 43 and the sum of the first 15 terms of the series is 120. Determine the first three terms of the series \n" ); document.write( "
Algebra.Com's Answer #366729 by issacodegard(60)![]() ![]() You can put this solution on YOUR website! Call the terms a_1,a_2,... then S_15=15*(a_1+a_15)/2=120. So, we solve for a_1, \n" ); document.write( "a_1=-27. Then we need to know the common difference, d. We know that a_n=a_1+(n-1)d. So, d=(43-(-27))/14=5. So, a_2=a_1+d=-22, and a_3=a_2+d=-17. \n" ); document.write( " |