Question

4x+5y-5z=196 -11x-7y+12z=-211 -8x-9y-z=-236 Solve for x y z

Answer 1

Answer in attachment.

x = -21, y = 46, z = -10

Answer 2

Have you learned matrices yet? I'm going to use that to solve these, please refer to the photos.

I solved the system by using a matrix calculation. The work always needs to be shown and you do that by setting up the matrix like in the first photo and also writing out all your equations. In a TI calculator, to do this you press 2ND-X^-1,GO TO EDIT - [A] - 3×4- now enter the coefficient of the system of equations variables. NOW 2ND MODE- 2ND-X^-1 -GO TO MATH- ALPHA APPS

Now, if you don't know this you may be confuse so after rref([A]) was enter a matrix came up with [1 0 0 -21] in the top row this means x equal -21. So, the next row is y and it came out as [0 1 0 46] so y equals 46 and I'm going to let you figure out what z is by looking at the matrix.

SO... X=-21 Y=46 and Z=-10

Let's Test it

$4x + 5y - 5z = 196 \\ 4( - 21) + 5(46) - 5( - 10) = 196 \\ - 84 + 230 + 50 = 196 \\ 196 = 196$