By substitution, we will see that the solution of the system is:
x = 13, y = 11, z = -1
The correct option is D.
Here we have a system of 3 equations:
x + y + 8z = 16
2x + 7z = 19
4x - 4y + 4z = 4
I will solve it by substitution, first, let's simplify the equations. Here we can divide the third equation by 4 so we remove all the common factors, then the system becomes:
x + y + 8z = 16
2x + 7z = 19
x - y + z = 1
Now, I will isolate x on the second equation:
x = (19 - 7z)/2 = (19/2) - (7/2)*z = 9.5 - 3.5*z
Now we can replace that on the other two equations:
(9.5 - 3.5*z) + y + 8z = 16
(9.5 - 3.5*z) - y + z = 1
Rewriting the system we get:
y + 4.5z = 6.5
-y - 2.5z = -8.5
Now we can isolate y on the first equation:
y = 6.5 - 4.5z
Replacing that on the other equation we get:
-( 6.5 - 4.5z) - 2.5z = -8.5
-6.5 + 4.5z - 2.5z = -8.5
2z = -8.5 + 6.5 = -2
z = -2/2 = -1
Then the value of y is:
y = 6.5 - 4.5z = 6.5 - 4.5*(-1) = 11
And the value of x is:
x = 9.5 - 3.5*z = 9.5 - 3.5*(-1) = 13
So the solution of the system is:
x = 13, y = 11, z = -1
The correct option is D.
If you want to learn more about systems of equations:
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