document.write( "Question 84282: When working with several different equations as a system such as below:\r
\n" );
document.write( "\n" );
document.write( "2X - Y + 4Z = -5
\n" );
document.write( "X + 2Y - Z = 6
\n" );
document.write( "X + Y + Z = 1\r
\n" );
document.write( "\n" );
document.write( "How many solutions are there ( none, 1, 3, or infinite) Please explain.\r
\n" );
document.write( "\n" );
document.write( "Thanks, I am a 48 year old male returning to college math after almost 30 years and am very confused right now...\r
\n" );
document.write( "\n" );
document.write( "Keith \n" );
document.write( "
Algebra.Com's Answer #60684 by checkley75(3666)![]() ![]() ![]() You can put this solution on YOUR website! THERE SHOULD BE 3 TOTAL SOLUTION: 1 FOR X, 1 FOR Y & 1 FOR Z. \n" ); document.write( "X+Y+Z=1 \n" ); document.write( "X+2Y-Z=6 NOW ADD THESE TWO EQUATIONS THUS: \n" ); document.write( "------------------------------------ \n" ); document.write( "2X+3Y=7 NOW SUBTRACT THE FIRST EAUATION \n" ); document.write( "-(2X-Y+4Z=-5) \n" ); document.write( "------------------------ \n" ); document.write( "4Y+4Z=12 REDUCING THIS EQUATIONWE GET: \n" ); document.write( "Y+Z=3 NIOW SUBSTITUTE 3 FOR (Y=Z) IN THE THIRD EQUATION THUS: \n" ); document.write( "X+3=1 \n" ); document.write( "X=1-3 \n" ); document.write( "X=-2 ANSWER. NOW SUBSTITUTE -2 FOR X IN THE EQUATION 2X+3Y=7 & SOLVE FOR Y: \n" ); document.write( "2*-2+3Y=7 \n" ); document.write( "-4+3Y=7 \n" ); document.write( "3Y=7+4 \n" ); document.write( "3Y=11 \n" ); document.write( "Y=11/3 ANSWER. \n" ); document.write( "-2+11/3+Z=1 \n" ); document.write( "Z=1+2-11/3 \n" ); document.write( "Z=3-11/3 \n" ); document.write( "Z=(9-11)/3 \n" ); document.write( "Z=-2/3 ANSWER. \n" ); document.write( "------------------------------------------------------------------------------- \n" ); document.write( "I'LL LEAVE THE PROOF UP TO YOU. IT'S GOOD PRACTICE TO SOLVE ALL THREE EQUATIONS. \n" ); document.write( " |