<PRE><B>Question 827342</B>
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x = length
y = width
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2x + 2y = 124
x = y + 12
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put the system of linear equations into standard form:
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2x + 2y = 124
x - y = 12
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copy and paste the above linear system in standard form into this matrix-method solver:
https://sooeet.com/math/system-of-linear-equations-solver.php
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solution:
x = length = 37 cm
y = width = 25 cm 
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system matrix
2 2
1 -1
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inverse of system matrix
0.25 0.5
0.25 -0.5
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determinant of system matrix = -4
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Solve and graph linear equations:
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Solve quadratic equations, quadratic formula:
https://sooeet.com/math/quadratic-formula-solver.php
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Solve systems of linear equations up to 6-equations 6-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php</PRE>