<PRE><B>Question 1155338</B>
There are 4 linear equations in 4 unknowns
:
(1)  -27a +9b -3c +d = -112
:
(2)  -a +b -c +d = -2
:
(3)  a +b +c +d = 4
:
(4)  8a +4b +2c +d = 13
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Any of the following methods can be used, elimination method, substitution method, Gauss-Seidel method, Cramer&#39;s Rule
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Note if you add equations 2 and 3 you get b +d = 1 and this can be used to eliminate a variable
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