Let f(y) = y^2- ky - 5. If f(2) = 7, then k

Step-by-step explanation:

So we have the function:

And we know that f(2)=7 and we want to find k.

So, substitute 2 for y and 7 for f(y). Thus:

Evaluate the square:

Subtract:

Add 1 to both sides:

Divide both sides by -2:

So, the value of k is -4.

And we're done!