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what is the substitution method of x+y=-2 and 2x-y=-4\r
\n" ); document.write( "\n" ); document.write( "x+y=-2---------------------eq1
\n" ); document.write( "2x-y=-4---------------------eq2\r
\n" ); document.write( "\n" ); document.write( "When we are solving a system of equations by substitution, the idea is to find the easiest approach. There is no rigid method to solving equations by substitution.\r
\n" ); document.write( "\n" ); document.write( "For your problem, here are the possibilities:
\n" ); document.write( "From eq1:
\n" ); document.write( "y=-2-x--------------substitute -2-x for y in eq2
\n" ); document.write( "or
\n" ); document.write( "x=-2-y---------------substitute -2-y for x in eq2
\n" ); document.write( "From eq2:
\n" ); document.write( "y=4+2x---------------substitute 4+2x for y in eq1
\n" ); document.write( "or
\n" ); document.write( "x=(-4-y)/2-------------substitute (-4-y)/2 for x in eq1\r
\n" ); document.write( "\n" ); document.write( "Any of the above substitutions will yield the correct answer but it appears that either of the first two may be the easiest.\r
\n" ); document.write( "\n" ); document.write( "I'll do the last one. It appears to be the most difficult:
\n" ); document.write( "(-4-y)/2+y=-2 multiply each term by 2
\n" ); document.write( "-4-y+2y=-4 subtract 4 from each side
\n" ); document.write( "-4+4-y+2y=-4+4 collect like terms
\n" ); document.write( "y=0--------------substitute y=0 into eq1
\n" ); document.write( "x+0=-2;
\n" ); document.write( "x=-2
\n" ); document.write( "CK
\n" ); document.write( "from eq1:
\n" ); document.write( "-2+0=-2
\n" ); document.write( "-2=-2
\n" ); document.write( "from eq2
\n" ); document.write( "2*-2-0=-4
\n" ); document.write( "-4=-4\r
\n" ); document.write( "\n" ); document.write( "Hope this helps---ptaylor\r
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