Question

Solve: 2x + 3y + 4z = 20, x + y + 2z = 9, 3x + 2y + z = 10

Answer 1

There are many methods for solve this linear system of three equations; I prefer "elimination method", that you express x from first equation and substitute into 2nd and 3rd equation. So you get 2 linear equations for 2 unknowns: y,z; Again you express y from one of this equations and substitue into second one. So you get single equation with unknown "z"., solve it. Get "z". Back substitute into "y-z" equation and get "y", and finally back substitute y,z into "x-y-z" equation and get "x"

You can check you solution with right solution:

http://www.hackmath.net/en/calculator/solving-system-of-linear-equations?input=2x+%2B+3y+%2B+4z+%3D+2%0D%0Ax+%2B+y+%2B+2z+%3D+9%0D%0A+3x+%2B+2y+%2B+z+%3D+10&submit=Calculate

x = 11.8
y = -16
z = 6.6