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What should be the value of k so that the system of equations has a solution?

-x + z - t = 3
2x + 2y - z - 7t = 14
3x - y - 8z - 6t = k

1 Answer

5 votes

Final answer:

To find the value of k that makes the system of equations have a solution, we need to solve the system of equations. By using the method of elimination and substitution, we find that the value of k is -21.

Step-by-step explanation:

To find the value of k that makes the system of equations have a solution, we need to solve the system of equations. The given system of equations is:

-x + z - t = 3

2x + 2y - z - 7t = 14

3x - y - 8z - 6t = k

We can solve this system of equations using the method of elimination. First, let's eliminate x from the second and third equations by multiplying the first equation by 2 and adding it to the second equation:

-2x + 2z - 2t = 6

2x + 2y - z - 7t = 14

3x - y - 8z - 6t = k

By adding these equations, we get:

2z - 2t - 7t = 20

2z - 9t = 20

Next, let's eliminate x from the third equation by multiplying the first equation by 3 and adding it to the third equation:

-3x + 3z - 3t = 9

3x - y - 8z - 6t = k

By adding these equations, we get:

3z - 11t = k + 9

Now we have a system of two equations with two variables (z and t). To solve this, we can use substitution or elimination. Let's use substitution:

From the equation 2z - 9t = 20, we can solve for z in terms of t as:

z = (20 + 9t) / 2

Substituting this value of z into the equation 3z - 11t = k + 9, we get:

3((20 + 9t) / 2) - 11t = k + 9

Simplifying this equation, we have:

30 + 27t - 11t = k + 9

16t + 30 = k + 9

16t - k = -21

Therefore, the value of k that makes the system of equations have a solution is -21.

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