Question

Solve x + y + z = -6
-2x – 2y – 2z = 8
5x + 5y + 5z = -30


Solve x + y + z = -6
-2x – 2y – 2z = 8
5x + 5y + 5z = -30

A Infinite number of solutions
B no solutions
C (1, -9, 3)
D (-1, -2, 3)

Answer 1

$-2x-2y-2x=8\iff x+y+z=-4$

$5x+5y+5z=-30\iff x+y+z=-6$

So the system reduces to

$\begin{cases}x+y+z=-6\\x+y+z=-4\end{cases}$

But $-6\neq-4$, so this system has no solutions.