Question: suppose the numbers x y z satisfy the following equations...
Suppose the numbers x, y, z satisfy the following equations, where a is some number:
x + y + z = 5- a
2x + y = 7 - a
x - y - 2z = 0
Use a matrix method to determine the values of x, y, and z, in terms of a. For what values of a will x, y, z all be positive?