solve the system of linear equations

-x+2y+z=5
-2x+7y-7z=31
3x-4y-9z=-1

Question

solve the system of linear equations

-x+2y+z=5
-2x+7y-7z=31
3x-4y-9z=-1

anonymous · Answer

i got as far as getting that y=7+3z and then i got stumped and i seem to be going in circles

experimentx · Answer

equate z from first equation to z from second equation => you will have equation in x and y equate z from first equation to z from third equation => you will have equation in x and y you will have two equations in x and y => solve it Or you can use cramers rule using matrices, http://www.wolframalpha.com/input/?i=-x%2B2y%2Bz%3D5%3B+-2x%2B7y-7z%3D31%3B+3x-4y-9z%3D-1%3B

experimentx · Answer

it seems that you have infinite solution for you system.

anonymous · Answer

i had this on a test and thats what i wrote but i got it wrong and the marker wrote that i had no proof that it had infinite solutions. thanks for your help though

experimentx · Answer

that marker was an idiot.

anonymous · Answer

:) i agree