SOLUTION: Solve this system of linear equations using matrices. x + y = 3 2y = 10 3x + 2y - 4z = 12 ------------------------------------ The answer is (-2

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 Question 633334: Solve this system of linear equations using matrices. x + y = 3 2y = 10 3x + 2y - 4z = 12 ------------------------------------ The answer is (-2, 5, 2); I want someone to walk me through this problem, because I'm just not able to solve it correctly using row operations. Here's my work: ------------------ 1 1 0 3 0 2 0 10 3 2 -4 12 ------------------ 1 1 0 3 0 2/2 0 10/2 3 2 -4 12 ------------------ 1 1 0 3 0 1 0 5 -3(1)+3 -3(1)+2 -4 -3(3)+12 ------------------ 1 1 0 3 0 1 0 5 0 1(1)-1 -4 1(3)+3 ------------------ 1 1 0 3 0 1 0 5 0 0 -4/-4 6/-4 ------------------ 1 1 0 3 0 1 0 2 0 0 1 -6/4 ------------------ I got z = -6/4, but it's supposed to equal 2... what am I doing wrong?Answer by richwmiller(9144)   (Show Source): You can put this solution on YOUR website!Actually the answer is -2, 5, -2 not -2, 5, 2 I don't know where you went wrong but after you found y=5 You could have gotten x=-2 1 1 0 3 0 1 0 5 1 0 0 -2 now we have 1 0 0-2 0 1 0 5 3 2 -4 12 3 0 0 -6 0 2 -4 18 0 2 0 10 0 0 -4 8 which leaves 0 0 1 -2