document.write( "Question 824678: Solve using matrices \r
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document.write( "-x+3y=6
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document.write( "3x-9y=9 \r
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document.write( "Help please! \n" );
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Algebra.Com's Answer #496679 by TimothyLamb(4379)![]() ![]() You can put this solution on YOUR website! --- \n" ); document.write( "-x+3y=6 \n" ); document.write( "3x-9y=9 \n" ); document.write( "--- \n" ); document.write( "copy and paste the above standard form linear equations in to this (matrix method) solver: \n" ); document.write( "https://sooeet.com/math/system-of-linear-equations-solver.php \n" ); document.write( "--- \n" ); document.write( "answer: \n" ); document.write( "This linear system is singular. It has no solution \n" ); document.write( "--- \n" ); document.write( "check by elimination method: \n" ); document.write( "--- \n" ); document.write( "-x + 3y = 6 \n" ); document.write( "3x - 9y = 9 \n" ); document.write( "--- \n" ); document.write( "-3x + 9y = 18 \n" ); document.write( "3x - 9y = 9 \n" ); document.write( "--- \n" ); document.write( "add the system: \n" ); document.write( "0 = 27 \n" ); document.write( "answer: \n" ); document.write( "This linear system is singular. It has no solution. \n" ); document.write( "NOTE: elimination method agrees with matrix method \n" ); document.write( "--- \n" ); document.write( "NOTE TO STUDENT: \n" ); document.write( "solving the system manually with matrices: \n" ); document.write( "--- \n" ); document.write( "A * X = B \n" ); document.write( "--- \n" ); document.write( "where A: \n" ); document.write( "[a b] = [-1 +3] \n" ); document.write( "[c d] = [+3 -9] \n" ); document.write( "where X: \n" ); document.write( "[x] \n" ); document.write( "[y] \n" ); document.write( "where B: \n" ); document.write( "[6] \n" ); document.write( "[9] \n" ); document.write( "--- \n" ); document.write( "[-1 +3][x] = [6] \n" ); document.write( "[+3 -9][y] = [9] \n" ); document.write( "--- \n" ); document.write( "solve for X: \n" ); document.write( "X = (A-inverse) * B \n" ); document.write( "--- \n" ); document.write( "where A-inverse: \n" ); document.write( "[-9 -3] * 1/dA \n" ); document.write( "[-3 -1] \n" ); document.write( "--- \n" ); document.write( "NOTE: \n" ); document.write( "let dA stand for \"the determinant of matrix A\" \n" ); document.write( "the determinant of A is a scalar (a real number) derived from matrix A ... \n" ); document.write( "--- \n" ); document.write( "dA = ad - bc \n" ); document.write( "dA = (-1*-9) - (3*3) \n" ); document.write( "dA = 9 - 9 \n" ); document.write( "dA = 0 \n" ); document.write( "--- \n" ); document.write( "1/dA = 1/0 \n" ); document.write( "but division by zero is undefined \n" ); document.write( "--- \n" ); document.write( "recall that A-inverse is: \n" ); document.write( "[-9 -3] * 1/dA \n" ); document.write( "[-3 -1] \n" ); document.write( "--- \n" ); document.write( "so A-inverse is undefined \n" ); document.write( "--- \n" ); document.write( "recall that: \n" ); document.write( "X = (A-inverse) * B \n" ); document.write( "--- \n" ); document.write( "so the solution vector X is undefined !!! \n" ); document.write( "--- \n" ); document.write( "answer: \n" ); document.write( "Therefore, this linear system is singular. It has no solution. \n" ); document.write( "NOTE: matrix-method solver agrees with elimination method, and both agree with the manual solution by matrices. \n" ); document.write( "--- \n" ); document.write( "Solve and graph linear equations: \n" ); document.write( "https://sooeet.com/math/linear-equation-solver.php \n" ); document.write( "--- \n" ); document.write( "Solve quadratic equations, quadratic formula: \n" ); document.write( "https://sooeet.com/math/quadratic-formula-solver.php \n" ); document.write( "--- \n" ); document.write( "Solve systems of linear equations up to 6-equations 6-variables: \n" ); document.write( "https://sooeet.com/math/system-of-linear-equations-solver.php \n" ); document.write( " |