document.write( "Question 1127067: 5;x;y is an arithmetic sequence and x;y;81 is a geometric sequence.All terms in the sequence are integers.calculate the value of x and y. \n" ); document.write( "
Algebra.Com's Answer #743448 by htmentor(1343)![]() ![]() You can put this solution on YOUR website! A.S. 5, x, y \n" ); document.write( "G.S. x, y, 81 \n" ); document.write( "Let d = the common difference of the A.S. \n" ); document.write( "Thus: \n" ); document.write( "x - 5 = d \n" ); document.write( "y - x = d \n" ); document.write( "y - 5 = 2d -> y - 5 = 2(x - 5) -> y = 2x - 5 \n" ); document.write( "So the terms of the G.S. are: \n" ); document.write( "x, 2x - 5, 81 \n" ); document.write( "The common ratio r = (2x - 5)/x = 81/(2x - 5) \n" ); document.write( "Solve for x: \n" ); document.write( "(2x - 5)/x = 81/(2x - 5) \n" ); document.write( "(2x - 5)^2 = 81x \n" ); document.write( "4x^2 - 101x + 25 = 0 \n" ); document.write( "This can be factored as (4x - 1)(x - 25) \n" ); document.write( "Since the terms are all integers, x = 25 \n" ); document.write( "Hence y = 2*25 - 5 = 45 \n" ); document.write( "Ans: x = 25, y = 45 \n" ); document.write( " \n" ); document.write( " |