Show that the system of equations 2x+6y=-11, 6x+20y-6z=-3, 6y-18z=-1 is not consistent.

1 answer

To show that the system is not consistent, we can use the method of elimination. We'll start by eliminating the variable z.

Multiplying the first equation by 3, we get 6x + 18y = -33.

Adding this equation to the second equation, we get:

(6x + 20y) + (6x + 18y) - 6z = -3 + (-33)
12x + 38y - 6z = -36.

But this equation is inconsistent with the third equation 6y - 18z = -1, as we cannot find values of x, y, and z that satisfy all three equations simultaneously. Therefore, the system of equations is not consistent.