The value of \( k \) represents the horizontal shift of the graph of the function. When you see a transformation like \( y = f(x - k) \), it indicates a shift to the right by \( k \) units. Conversely, \( y = f(x + k) \) would indicate a shift to the left by \( k \) units.
To determine the correct value of \( k \) based on the given information, you would need to know the specifics of the horizontal shift in the graph. Without seeing the shift explicitly, I can't tell you which of the values \( 10, 8, 5, \) or \( 2 \) is correct.
Generally, if the graph has moved to the right, you would take \( k \) as positive. If it's moved to the left, you would take \( k \) as negative.
If you have the specifics of the shift (such as how far the graph of \( y = f(x) \) has moved to the right or left), please provide that, and I can help you determine the correct value for \( k \).