document.write( "Question 1130421: Solve the system of equations by the elimination method. (If the system is dependent, let y = c and enter a general solution in terms of c. If there is no solution, enter NO SOLUTION.)
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Algebra.Com's Answer #747087 by ikleyn(53765) $\"\"$ $\"About$

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document.write( "4x + 7y =  28        (1)\r\n" );
document.write( "5x - 4y = -16        (2)\r\n" );
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document.write( "Multiply eq(1) by 5 (both sides).  Multiply eq(2) by 4 (both sides).  You will get\r\n" );
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document.write( "20x + 35y =  140      (3)\r\n" );
document.write( "20x - 16y = -64       (4)\r\n" );
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document.write( "Subtract eq(4) from eq(2).  The terms  \" 20x \" will cancel each other, and you will get a single equation for the unknown \"y\" only.\r\n" );
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document.write( "It is how the Elimination method works.\r\n" );
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document.write( "      35y - (-16y) = 140 - (-64)\r\n" );
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document.write( "      51y = 204\r\n" );
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document.write( "        y = 204/51 = 4.\r\n" );
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document.write( "Now substitute the value y= 4 into eq(1). You will get\r\n" );
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document.write( "     4x + 7*4 = 28\r\n" );
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document.write( "     4x = 28 - 28 = 0\r\n" );
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document.write( "      x = 0.\r\n" );
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document.write( "Answer.  x= 0;  y= 4.\r\n" );
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document.write( "CHECK.  Check the solution on your own by substituting the ontained values into each of the two given equations.\r\n" );
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