Question

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

Answer 1

`k=-4`

Explanation:

So we have the function:

`f(y)=y^2-ky-5`

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

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

`7=(2)^2-k(2)-5`

Evaluate the square:

`7=4-2k-5`

Subtract:

`7=-2k-1`

Add 1 to both sides:

`8=-2k`

Divide both sides by -2:

`k=-4`

So, the value of k is -4.

And we're done!