document.write( "Question 1131011: Solve the systems of equations by using the substitution method. (If the system is dependent, enter a general solution in terms of c
\n" ); document.write( "{6x+ 7y = −9
\n" ); document.write( " 2x+ 5y =5\r
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Algebra.Com's Answer #747646 by ikleyn(52787) $\"\"$ $\"About$

You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "Let me show to you much MORE REASONABLE way to solve it by the Substitution method.\r
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document.write( "6x + 7y = -9      (1)\r\n" );
document.write( "2x + 5y =  5      (2)\r\n" );
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document.write( "The term \" 6x \" in equation (1) is three times the term \"2x\" in the in equation (2).\r\n" );
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document.write( "Therefore, it is TOTALLY ENOUGH to express 2x from equation (2) as  2x = 5 - 5y  and then substitute it into \r\n" );
document.write( "equation (1), replacing \" 6x \" there  as 3*(2x). You will get then\r\n" );
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document.write( "    3*(5-5y) + 7y = -9\r\n" );
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document.write( "    15 - 15y + 7y = -9\r\n" );
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document.write( "    -8y = -9 - 15 = -24\r\n" );
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document.write( "    y  =  = 3.\r\n" );
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document.write( "Now substitute this value  y= 3 into equation (2) to get\r\n" );
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document.write( "    2*x + 5*3 = 5\r\n" );
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document.write( "    2x + 15 = 5\r\n" );
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document.write( "    2x = 5 - 15 = -10\r\n" );
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document.write( "    x =  = -5.\r\n" );
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document.write( "Answer.  The solution is  x= -5,  y= 3.\r\n" );
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document.write( "Check the solution on your own by substituting the found values into the given equations.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved.\r
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\n" ); document.write( "\n" ); document.write( "By doing in this way, you avoid working with fractions and denominators.\r
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\n" ); document.write( "\n" ); document.write( "Less computing - less chance to make an error.\r
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