For this case we must find the inverse of the following function:
![f (x) = x ^ 2 + 7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/x1prrmniwv4c91ui1eqjykfywfu53bb0mx.png)
For this we follow the steps below:
Replace f(x) with y:
![y = x ^ 2 + 7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/f5qlp0t09h4uvbdcw9fr749zo0xeqvv84o.png)
We exchange the variables:
![x = y ^ 2 + 7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/994bitao5g829rgye82dyrktaz671vnl8x.png)
We solve the equation for "y", that is, we clear "y":
![y^ 2 + 7 = x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/npwb2ydfsfg29igk095mx5sof6s8dni6hs.png)
We subtract 7 on both sides of the equation:
![y ^ 2 = x-7](https://img.qammunity.org/2020/formulas/mathematics/middle-school/razglx29aug0hi3itbzprn3nhrvdfakcy2.png)
We apply square root on both sides of the equation to eliminate the exponent:
![y = \pm\sqrt {x-7}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/jj9k2ye4n0krwf28r70i8hqb5udu6k6nxn.png)
We change y by
![f ^ {- 1} (x):](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ggc3z2p7x17msi7c3efapzety0ez3x7d5b.png)
![f ^ {- 1} (x) =\pm\sqrt {x-7}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/7yn3rc41f3y8w3m21l15ao12olci7fsaet.png)
Answer;
Option A