Solve the system: 2x-3y-z=5 -2x+3y+z=-5 8x-12y-4z+20 How I understand it is the 2x+-2x along with the -3y+3y and -z+z can cancel each other out. I am having trouble figuring out what to do next. Any help will be appreciated! 9/16/2013 | Courtnee from Mitchell, IN | 2 Answers | 0 Votes Mark favorite Subscribe Comment
Hey Courtnee -- its often helpful add/subtract expressions, sometimes doubling/halving them ... here we don't have 3 different expressions: (2) is the negative of (1), (3) is (1) rescaled by 4 :) 9/16/2013 | Brad M. Comment
We have one equation with three variables: 2x-3y-z=5 (Your other two equations are just multiples of this equation.) You can solve it for any one variable, eg. z=2x-3y-5 which has infinitely many solutions, namely all points of the form (x,y,2x-3y-5), where x and y are any real numbers. Geometrically, the solution set corresponds to a plane in 3-space. 9/16/2013 | Andre W. Comment