document.write( "Question 29049: Solve the system by addition
\n" ); document.write( " –4x + 5y = 1
\n" ); document.write( " x – 4y = 19
\n" ); document.write( " \n" ); document.write( "
Algebra.Com's Answer #15904 by sdmmadam@yahoo.com(530)\"\" \"About 
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Solve the system by addition
\n" ); document.write( " –4x + 5y = 1 ----(1)
\n" ); document.write( " x – 4y = 19 ----(2)X4
\n" ); document.write( "The stipulation is to solve by addition
\n" ); document.write( "Observe that one coefficient of x is (-4) and the other is 1
\n" ); document.write( "So multiply equation (2) by 4
\n" ); document.write( " 4x-16y= 76 ----(3)
\n" ); document.write( "And –4x + 5y = 1 ----(1)
\n" ); document.write( "(3)+(1) implies
\n" ); document.write( "(4x-4x)+(-16y+5y) = (76+1)
\n" ); document.write( "0-11y = 77
\n" ); document.write( "-11y = 77
\n" ); document.write( "y = 77/(-11) (7X11)/(-11) = -7 (cancelling 11)
\n" ); document.write( "y = -7
\n" ); document.write( "Putting y = -7 in (2)
\n" ); document.write( "x-4y =19
\n" ); document.write( "x-4X(-7) = 19
\n" ); document.write( "x+28 = 19
\n" ); document.write( "x = 19-28
\n" ); document.write( "x=-9
\n" ); document.write( "Answer: x= -9 and y =-7
\n" ); document.write( "Verification: Putting x= -9 and y =-7 in the other equation, that is in (1)
\n" ); document.write( "–4x + 5y = 1 ----(1)
\n" ); document.write( "LHS= -4x+5y =-4X(-9)+5X(-7) = 36-35 = 1 =RHS
\n" ); document.write( "Therefore our values are correct. \n" ); document.write( "
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