## Intermediate Algebra for College Students (7th Edition)

The fill in the blanks are $-2$ $-4$.
The given equations are $x+y-z=-1$ ... (1) $2x-2y-5z=7$ ... (2) $4x+y-2z=7$ ... (3) Multiply the equation (1) by $-2$ $(-2)\cdot x+(-2)\cdot y-(-2)\cdot z=-(-2)\cdot 1$ $-2x-2y+2z=2$ ... (4) Now add equation (4) and equation (2). $-2x-2y+2z+2x-2y-5z=2+7$ add like terms $-4y-3z=9$ $x$ eliminated. Multiply the equation (1) by $-4$ $(-4)\cdot x+(-4)\cdot y-(-4)\cdot z=-(-4)\cdot 1$ $-4x-4y+4z=4$ ... (5) Now add equation (5) and equation (3). $-4x-4y+4z+4x+y-2z=4+7$ $-3y+2z=11$ $x$ eliminated.