document.write( "Question 572588: solve by elimination
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document.write( "6x-9y=13.5
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document.write( "7y-3x=-8 \n" );
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Algebra.Com's Answer #368603 by mathsmiles(68)![]() ![]() You can put this solution on YOUR website! I'm going to guess here on what your \"elimination\" term means, only because I hate leaving you high and dry. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "6x - 9y = 13.5 (I already hate this one btw) \n" ); document.write( "7y - 3x = -8\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "First thing we're going to do is line up the x's and y's since they were too lazy to do that for you: \n" ); document.write( "6x - 9y = 13.5 (unchanged) \n" ); document.write( "-3x+ 7y = -8 (reversed the first two terms)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now if we multiply the 2nd equation (both sides) by 2, we have something interesting in the x column: \n" ); document.write( "2(-3x + 7y) = 2(-8) \n" ); document.write( "-6x + 14y = -16\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Rewriting the two equations with this change: \n" ); document.write( "6x - 9y = 13.5 (unchanged again) \n" ); document.write( "-6x + 14y = -16 \n" ); document.write( "What you'll notice is if we add these two equations vertically, the x factors cancel out so we get:\r \n" ); document.write( "\n" ); document.write( "0 -9y + 14y = 13.5 - 16 \n" ); document.write( "5y = -2.5 \n" ); document.write( "Divide both sides by 5 \n" ); document.write( "y = -.5\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "But we still need x: \n" ); document.write( "6x - 9(-.5) = 13.5 Multiplying the 9 by .5 and signs cancel: \n" ); document.write( "6x + 4.5 = 13.5 \n" ); document.write( "Subtract 4.5 from both sides leaving: \n" ); document.write( "6x = 9 \n" ); document.write( "x = 9/6 = 3/2 = 1.5 (did they have to?? I like whole numbers myself ;-)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Checking: \n" ); document.write( "Equation 1: \n" ); document.write( "6(1.5)-9(-.5) = 13.5 \n" ); document.write( "9 + 4.5 = 13.5 (you'll want to do this step for yourself, but all I did was multiply) \n" ); document.write( "13.5 = 13.5 Correct! \n" ); document.write( " \r \n" ); document.write( "\n" ); document.write( "Equation 2: \n" ); document.write( "7(-.5) - 3(1.5) = -8 \n" ); document.write( "-3.5 - 4.5 = -8 \n" ); document.write( "-8 = -8 Correct!\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Good luck! And please leave me feedback if I was correct in the definition of \"elimination\". :-) \n" ); document.write( " \n" ); document.write( " |