document.write( "Question 188345: I do not know where to start. When do you multiply numbers to the x and y.
\n" ); document.write( "my problem is this
\n" ); document.write( "2x+y = 5
\n" ); document.write( "-6x - 3y = -15 My teacher said that you multiply the 2x and the y by 3 why? and how do you finish after that? \n" ); document.write( "
Algebra.Com's Answer #141187 by Alan3354(69443)\"\" \"About 
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I do not know where to start. When do you multiply numbers to the x and y.
\n" ); document.write( "my problem is this
\n" ); document.write( "2x+y = 5
\n" ); document.write( "-6x - 3y = -15 My teacher said that you multiply the 2x and the y by 3 why? and how do you finish after that?
\n" ); document.write( "------------------
\n" ); document.write( "In order to eliminate one of the variables, you multiply one of the equations by something to get the same coefficients. In this case, multiplying the 1st eqn by 3 gives 6x + 3y = 15. The coeff's for x and y are the same as in the other equation. That's the reason to multiply by 3.
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\n" ); document.write( "In this example, tho, the 2 equations are actually the same. If you add them (after multiplying by 3) you get 0x + 0y = 0.
\n" ); document.write( "There is no unique solution for this pair of eqns.
\n" ); document.write( "If you graph them, you get the same line 2 times. \n" ); document.write( "
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