document.write( "Question 203642: the following is known about three numbers: if the second number is subtracted from the sum of the first number and 5 times the third number, the result is -7. the third number plus 5 times the first number is -1. the first number plus 3 times the second number plus the third number is 5. find the three numbers.
\n" );
document.write( "[hint: let x represent the first number, y the second number, and z the third number. use the given conditions to write and solve a system of equations.] \n" );
document.write( "
Algebra.Com's Answer #153643 by stanbon(75887)![]() ![]() ![]() You can put this solution on YOUR website! the following is known about three numbers: x, y, z \n" ); document.write( "if the second number is subtracted from the sum of the first number and 5 times the third number, the result is -7. \n" ); document.write( "(x+5z)-y = -7 \n" ); document.write( "---------------------- \n" ); document.write( "the third number plus 5 times the first number is -1. \n" ); document.write( "z+5x = -1 \n" ); document.write( "---------------------- \n" ); document.write( "the first number plus 3 times the second number plus the third number is 5. find the three numbers. \n" ); document.write( "x+3y+z = 5 \n" ); document.write( " \n" ); document.write( "------------------------------------ \n" ); document.write( "Rearrange to get: \n" ); document.write( "x - y + 5z = -7 \n" ); document.write( "5x + 0y +z = -1 \n" ); document.write( "x + 3y + z = 5 \n" ); document.write( "------------------- \n" ); document.write( "Multiply thru the 1st equation by 3 \n" ); document.write( "3x - 3y + 15z = -21 \n" ); document.write( "----- \n" ); document.write( "Add that to the 3rd equation to get: \n" ); document.write( "4x +16z = -16 \n" ); document.write( "---- \n" ); document.write( "Group that with the 2nd equation to solve for x and z: \n" ); document.write( "5x + z = -1 \n" ); document.write( "4x +16z = -16 \n" ); document.write( "---------------------- \n" ); document.write( "Multiply thru the 1st equation by 16; then solve for \"x\": \n" ); document.write( "80x + 16z = -16 \n" ); document.write( "4x + 16z = -16 \n" ); document.write( "---------------------- \n" ); document.write( "Subtract the 2nd from the 1st to get: \n" ); document.write( "76x = 0 \n" ); document.write( "x = 0 \n" ); document.write( "--- \n" ); document.write( "Substitute that into 4x+16z = -16 to get: \n" ); document.write( "z = -1 \n" ); document.write( "------------------- \n" ); document.write( "Substitute those values into x-y+5z = -7 to solve for \"y\": \n" ); document.write( "0 -y +5(-1)=-7 \n" ); document.write( "-y-5=-7 \n" ); document.write( "-y = -2 \n" ); document.write( "y = 2 \n" ); document.write( "------------------\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "x = 0 \n" ); document.write( "y = 2 \n" ); document.write( "z = -1 \n" ); document.write( "------------ \n" ); document.write( "Cheers, \n" ); document.write( "Stan H.\r \n" ); document.write( "\n" ); document.write( " \n" ); document.write( " |