document.write( "Question 1057496: Using \"Completing the Square\" to find ALL solutions for: X^2-6x=40\r
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document.write( "How do you find ALL solutions? \n" );
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Algebra.Com's Answer #672533 by solve_for_x(190)![]() ![]() ![]() You can put this solution on YOUR website! Complete the square by adding the square of half of the coefficient of the \"x\"-term to both sides.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x^2 - 6x = 40\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The coefficient of the x term is -6. Half of that is -3. And -3 squared is 9.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Adding 9 to both sides gives:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x^2 - 6x + 9 = 49\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The left side can be factored as a perfect square:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(x - 3)^2 = 49\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Taking the square root of both sides then gives:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x - 3 = ±7\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Adding 3 to both sides gives solutions for x:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 3 ± 7\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The solutions are:\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 3 - 7 = -4\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 3 + 7 = 10\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Thus, the set of solutions is x = -4 and x = 10.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "You can confirm this by rearranging the original equation as x^2 - 6x - 40 = 0, and then \n" ); document.write( "using the Quadratic Formula to get the solutions for x. \n" ); document.write( " |