# SOLUTION: The sum of the first six terms of an A.P is 72 and the second term is seven times the fifth term. Form two equations in a' and d' and solve them to find the first term and the comm

Algebra ->  Algebra  -> Sequences-and-series -> SOLUTION: The sum of the first six terms of an A.P is 72 and the second term is seven times the fifth term. Form two equations in a' and d' and solve them to find the first term and the comm      Log On

 Ad: Algebrator™ solves your algebra problems and provides step-by-step explanations! Ad: Algebra Solved!™: algebra software solves algebra homework problems with step-by-step help!

 Algebra: Sequences of numbers, series and how to sum them Solvers Lessons Answers archive Quiz In Depth

 Question 127233: The sum of the first six terms of an A.P is 72 and the second term is seven times the fifth term. Form two equations in a' and d' and solve them to find the first term and the common diffrence. Thanks and pls help!Answer by solver91311(16885)   (Show Source): You can put this solution on YOUR website!The first term is a, the second term is a + d, the third, a + 2d, etc. So the sum of the first 6 terms is . The 15 comes from So our first equation is The second term is and the fifth term is , so the second equation is: , which simplifies to Add the two equations, since the coefficients on the a terms are already additive inverses Substitute this value for d into the first equation: Check: Answer checks.