document.write( "Question 254675: Three numbers form an arithmetic sequence, common difference being 11. If first number is decreased by 6, second number decreased by 1, and third number doubled, resulting numbers form a geometric sequence. determine the numbers that form the arithmetic sequence\r
\n" );
document.write( "\n" );
document.write( "Answer is -26, -15, -4, 14, 25, 36 \n" );
document.write( "
Algebra.Com's Answer #187022 by drk(1908)![]() ![]() ![]() You can put this solution on YOUR website! Let the first term be A \n" ); document.write( "Let the second term be A + 11 \n" ); document.write( "Let the third term be A + 22 \n" ); document.write( "we know that common difference, d, is 11. \n" ); document.write( "-- \n" ); document.write( "A - 6, A + 10, 2(A+22) \n" ); document.write( "is now a geometric sequence. They have common ratios which can be expressed as \n" ); document.write( "(A+10)/(A-6) = (2A+44)/(A+10) \n" ); document.write( "Cross multiplying, we get \n" ); document.write( "(A+10)^2 = (2A+44)(A-6) \n" ); document.write( "A^2 + 20A + 100 = 2A^2 + 32A -264 \n" ); document.write( "set = 0 as \n" ); document.write( "A^2 + 12A -364 = 0 \n" ); document.write( "(A - 14)(a + 26) = 0 \n" ); document.write( "A = 14 or A = -26 \n" ); document.write( "-- \n" ); document.write( "If A = 14, then the arithmetic sequence is \n" ); document.write( "14, 25, 36 \n" ); document.write( "and the geometric sequence is \n" ); document.write( "8, 24, 72 \n" ); document.write( "-- \n" ); document.write( "If A = -26, then the arithmetic sequence is \n" ); document.write( "-26, -15, -4 \n" ); document.write( "and the geometric sequence is \n" ); document.write( "-32, -16, -8 \n" ); document.write( " |