Chapter 9 - Section 9.1 - Solving Systems of Linear Equations in Three Variables and Problem Solving - Vocabulary and Readiness Check - Page 637: 2

a, c, d

$(2, 1, -4)$ $x+y+z=-1$ $2+1-4=-1$ $3-4=-1$ is true $x-y-z=-3$ $2-1-(-4)=-3$ $1+4=-3$ $5 = -3$ is not true $2x-y+z=-1$ $2*2-1+(-4)=-1$ $4-1-4=-1$ $3-4=-1$ is true $-x-3y-z=-1$ $-(x+3y+z)=-1$ $-(2+3*1-4)=-1$ $-(2+3-4)=-1$ $-(5-4)=-1$ $-1=-1$ is true