document.write( "Question 1131020: Use the method of substitution to solve the following system of equations. If the system is dependent, express the solution set in terms of one of the variables. Leave all fractional answers in fraction form.\r
\n" ); document.write( "\n" ); document.write( "{7x+8y=−18
\n" ); document.write( "7x+5y=−6
\n" ); document.write( "so I first isolated y on the first equation, getting (-7x-18)/8. then i substituted it for y in the second equation getting x=-3.
\n" ); document.write( "I then substituted -3 for x on the first and second equation getting 3/8 and -3.
\n" ); document.write( "I dont know what I'm doing, if I'm doing it right and if it is a dependent system inconsistent or only one solution. Please help if you can, Thank You! \n" ); document.write( "

Algebra.Com's Answer #747644 by ikleyn(52798) $\"\"$ $\"About$

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( "7x + 8y = -18      (1)\r\n" );
document.write( "7x + 5y =  -6      (2)\r\n" );
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document.write( "The term \" 7x \" is in the first and in the second equation.\r\n" );
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document.write( "Therefore, it is TOTALLY ENOUGH to express 7x from the first equation as  7x = -18 - 8y  and then substitute it into \r\n" );
document.write( "the second equation, replacing \" 7x \" there. You will get then\r\n" );
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document.write( "    (-18-8y) + 5y = -6\r\n" );
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document.write( "    -18 - 8y + 5y = -6\r\n" );
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document.write( "    -3y = -6 + 18 = 12\r\n" );
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document.write( "    y  =  = -4.\r\n" );
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document.write( "Now substitute this value  y= -4 into equation (2) to get\r\n" );
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document.write( "    7x + 5*(-4) = -6\r\n" );
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document.write( "    7x - 20 = -6\r\n" );
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document.write( "    7x = -6 + 20 = 14\r\n" );
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document.write( "    x = 14/7 = 2.\r\n" );
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document.write( "Answer.  The solution is  x= 2,  y= -4.\r\n" );
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document.write( "Check the solution on your own by substituting the found values in 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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