document.write( "Question 176635: Solve the following systems using inverse matrices. can you also show me the steps.. thanks\r
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\n" ); document.write( "\n" ); document.write( "2x - y = 2
\n" ); document.write( "2x - 2y = 4\r
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\n" ); document.write( "\n" ); document.write( "2x + 3y + 4z = 3
\n" ); document.write( "-13x + 5y - 2z = 3
\n" ); document.write( "-3x + 4y + 3z = 6
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Algebra.Com's Answer #131732 by Mathtut(3670)\"\" \"About 
You can put this solution on YOUR website!
2x - y = 2
\n" ); document.write( "2x - 2y = 4
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\n" ); document.write( "matrix A =\"%28matrix%282%2C2%2C2%2C-1%2C2%2C-2%29%29\"
\n" ); document.write( "matrix C =\"%28matrix%282%2C1%2C2%2C4%29%29\"
\n" ); document.write( "adj A=\"%28matrix%282%2C2%2C-2%2C1%2C-2%2C2%29%29\" the adjunct of a 2x2 matrix is the matrix in which the main diagonal elements are switched and the other elements are multiplied by -1.
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\n" ); document.write( "the inverse of A or \"A%5E-1\" is
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\n" ); document.write( "so det A=-2(2)-2(-1)=-2--->-1/2\r
\n" ); document.write( "\n" ); document.write( "\"A%5E-1\"=(1/det A)(adj A)=-1/2\"%28matrix%282%2C2%2C-2%2C1%2C-2%2C2%29%29\"=\"%28matrix%282%2C2%2C1%2C-1%2F2%2C1%2C-1%29%29\"
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\n" ); document.write( "now finally the answer is found by multiplying the inverse of A by matrix C\"A%5E-1\"mat C
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\n" ); document.write( " \"%28matrix%282%2C2%2C1%2C-1%2F2%2C1%2C-1%29%29\"\"%28matrix%282%2C1%2C2%2C4%29%29\"=\"%28matrix%282%2C1%2C0%2C-2%29%29\"
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\n" ); document.write( "so x=0 and y=-2
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\n" ); document.write( "2x + 3y + 4z = 3
\n" ); document.write( "-13x + 5y - 2z = 3
\n" ); document.write( "-3x + 4y + 3z = 6
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\n" ); document.write( "RHS is the numbers on the right hand side of the equation.
\n" ); document.write( "C1 is column 1...etc
\n" ); document.write( "R1 is row 1...etc\r
\n" ); document.write( "\n" ); document.write( ":Matrix A \"%28matrix%283%2C3%2C2%2C3%2C4%2C-13%2C5%2C-2%2C-3%2C4%2C3%29%29\"
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\n" ); document.write( "det A is the determinant of A
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\n" ); document.write( "det A=(2) det\"%28matrix%282%2C2%2C5%2C-2%2C4%2C3%29%29\"-(-13)det\"%28matrix%282%2C2%2C3%2C4%2C4%2C3%29%29\"+(-3)det\"%28matrix%282%2C2%2C3%2C4%2C5%2C-2%29%29\"=46-91+78=33
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\n" ); document.write( "det A=13
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\n" ); document.write( "matrix A(C1 replaced with RHS) lets call A1
\n" ); document.write( "A1=\"%28matrix%283%2C3%2C3%2C3%2C4%2C3%2C5%2C-2%2C6%2C4%2C3%29%29\"
\n" ); document.write( "det A1=b>(3) det\"%28matrix%282%2C2%2C5%2C-2%2C4%2C3%29%29\"-(3)det\"%28matrix%282%2C2%2C3%2C4%2C4%2C3%29%29\"+(6)det\"%28matrix%282%2C2%2C3%2C4%2C5%2C-2%29%29\"=69+21-156=-66
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\n" ); document.write( "matrix A(C2 replaced with RHS) lets call A2
\n" ); document.write( "A2=\"%28matrix%283%2C3%2C2%2C3%2C4%2C-13%2C3%2C-2%2C-3%2C6%2C3%29%29\"
\n" ); document.write( "det A2=b>(2) det\"%28matrix%282%2C2%2C3%2C-2%2C6%2C3%29%29\"-(-13)det\"%28matrix%282%2C2%2C3%2C4%2C6%2C3%29%29\"+(-3)det\"%28matrix%282%2C2%2C3%2C4%2C3%2C-2%29%29\"=42-195+54=-99
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\n" ); document.write( "matrix A(C3 replaced with RHS) lets call A3
\n" ); document.write( "A3=\"%28matrix%283%2C3%2C2%2C3%2C3%2C-13%2C5%2C3%2C-3%2C4%2C6%29%29\"
\n" ); document.write( "det A3=b>(2) det\"%28matrix%282%2C2%2C5%2C3%2C4%2C6%29%29\"-(-13)det\"%28matrix%282%2C2%2C3%2C3%2C4%2C6%29%29\"+(-3)det\"%28matrix%282%2C2%2C3%2C3%2C5%2C3%29%29\"=36+78+18=132
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\n" ); document.write( "\"x=det+A1%2Fdet+A=-66%2F33=highlight%28-2%29\"
\n" ); document.write( "\"x=det+A2%2Fdet+A=-99%2F33=highlight%28-3%29\"
\n" ); document.write( "\"x=det+A3%2Fdet+A=132%2F33=highlight%284%29\"\r
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