document.write( "Question 1033513: The sum of two numbers is 1 and the sum of their squares is 13. What is the sum of their cubes? \n" ); document.write( "
Algebra.Com's Answer #648142 by ankor@dixie-net.com(22740) You can put this solution on YOUR website! The sum of two numbers is 1 \n" ); document.write( "a + b = 1 \n" ); document.write( "a = (-b+1) \n" ); document.write( " and the sum of their squares is 13. \n" ); document.write( "a^2 + b^2 = 13 \n" ); document.write( "Replace a with (-b+1) \n" ); document.write( "(-b+1)^2 + b^2 = 13 \n" ); document.write( "FOIL (-b+1)(-b+1) \n" ); document.write( "b^2 - 2b + 1 + b^2 = 13 \n" ); document.write( "a quadratic equation \n" ); document.write( "2b^2 - 2b - 12 = 0 \n" ); document.write( "simplify, divide by 2 \n" ); document.write( "b^2 - b - 6 = 0 \n" ); document.write( "Factors to \n" ); document.write( "(b-3)(b+2) = 0 \n" ); document.write( "Two solution pairs, essentially the same \n" ); document.write( "b = 3, then a = -2 \n" ); document.write( " and \n" ); document.write( "b = -2, then a = 3 \n" ); document.write( ": \n" ); document.write( "What is the sum of their cubes? \n" ); document.write( " 3^3 + -2^3 = 27 - 8 = 19 \n" ); document.write( ": \n" ); document.write( ": \n" ); document.write( "Check in the 2nd equation \n" ); document.write( "3^2 + -2^2 = 9 + 4 = 13\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |