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Question 80447: You have to solve the equations using matrices. I can get part of the answer correct but not the whole answer. I can solve for y, but what I come up with for x is not correct according to the book. The two equations are:
12x + 2y = 2 and 6x - 3y = -11
I can come up with 3 for y but I end up with -11/6 for x and the book says it should be -1/3. I can't figure out how to get the -1/3.
Answer by Edwin McCravy(20063)   (Show Source):
You can put this solution on YOUR website! : You have to solve the equations using matrices. I can get part of the answer correct but not the whole answer. I can solve for y, but what I come up with for x is not correct according to the book. The two equations are:
12x + 2y = 2 and 6x - 3y = -11
I can come up with 3 for y but I end up with -11/6 for x and the book says it should be -1/3. I can't figure out how to get the -1/3.
12x + 2y = 2
6x - 3y = -11
[12 2 | 2]
[ 6 -3 | -11]
Get a 0 where the 6 is by adding -1
times the top row to 2 times the
bottom row:
-1[12 2 | 2]
2[ 6 -3 | -11]
[12 2 | 2]
[ 0 -8 | -24]
Get a 0 where the first 2 is in the top
row by adding 1 times the bottom
row to 4 times the top row
4[12 2 | 2]
1[ 0 -8 | -24]
[48 0 | -16]
[ 0 -8 | -24]
Now divide the top row thru by 48
and the bottom row by -8:
[1 0 | -1/3]
[0 1 | 3 ]
So the solution is x = -1/3, y = 3
Edwin
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