SOLUTION: A rectangles length is 4 less than triple it's width. If the perimeter of the rectangle is 40, find the area of the rectangle.

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Question 828692: A rectangles length is 4 less than triple it's width. If the perimeter of the rectangle is 40, find the area of the rectangle.
Answer by TimothyLamb(4379) About Me  (Show Source):
You can put this solution on YOUR website!
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x = 3y - 4
2x + 2y = 40
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put the system of linear equations into standard form:
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x - 3y = -4
2x + 2y = 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 = 14
y = 6
area = xy = 14*6 = 84 sq.units
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system matrix
1 -3
2 2
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inverse of system matrix
0.25 0.375
-0.25 0.125
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determinant of system matrix = 8
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