Use the 5-step procedure to solve by substitution: x - y + 2z = 7, 2x + y + z = 8, and x - z = 5

Answer 1

Per eq 3

x = z+5

eq 1 becomes: z+5 - y + 2z = 7

3z - y = 2

eq 2 becomes: 2(z+5) + y + z =8

2z + 10 + y + z = 8

3z + y = -2

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Then 3z = y+2 and 3z = -2 - y

so y+2 = -2 - y

2y = -4

y = -2

then 3z + -2 = -2

3z = 0

z=0

this forces x=5

{x=5, y = -2, z=0} is the solution