Final answer:
The three lines have a common point of intersection for any value of k.
Step-by-step explanation:
To find the values of k for which the three lines have a common point of intersection, we need to solve the system of equations:
x + y = 12
kx - y = 0
y - x = 2k
First, let's rewrite the second equation as y = kx. We can substitute this into the other equations to eliminate y:
x + kx = 12
y - x = 2k
Combining like terms, we get:
(1 + k)x = 12
2k + x = y
Now, we can substitute y = 2k + x into the first equation:
x + kx = 12
(1 + k)x = 12
This equation holds true for all values of x and k, so the three lines have a common point of intersection for any value of k.