<PRE><B>Question 825499</B>
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x = 25 cent coins
y = 50 cent coins
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25x + 50y = 13000
y = 2x - 40
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put the system of linear equations into standard form
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25x + 50y = 13000
2x - y = 40
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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 = 25 cent coins = 120
y = 50 cent coins = 200
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system matrix
25 50
2 -1
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inverse of system matrix
0.008 0.4
0.016 -0.2
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determinant of system matrix = -125
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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 4-equations 4-variables:
https://sooeet.com/math/system-of-linear-equations-solver.php</PRE>