Answer:
![1 + √(14)](https://img.qammunity.org/2021/formulas/mathematics/college/cranumzq4vmgzr1yo08umft05ywskb55wu.png)
Explanation:
Using pythagorean theorem, x and x+6 are the legs, and x+7 is the hypotenuse.
You can express this as an equation.
![x^2 + (x+6)^2 = (x+7)^2](https://img.qammunity.org/2021/formulas/mathematics/college/rot9996p0c5sf5f45lhz0z5vm2vc6x7nv2.png)
Expanding, this is
![x^2+x^2+12x+36 = x^2+14x+49](https://img.qammunity.org/2021/formulas/mathematics/college/m3men6x7k18zr7a1gcpkch61326p5m1yyd.png)
Grouping up, this is
![2x^2+12x+36 = x^2+14x+49](https://img.qammunity.org/2021/formulas/mathematics/college/egb96jmw3bwh7ccm0ni9q5gmkesv8cdq5z.png)
Rearranging, this is
![x^2-2x-13 = 0](https://img.qammunity.org/2021/formulas/mathematics/college/b7h62wmp7stiwhd0xoqso0lrc9yja0lwng.png)
Now, we can use the quadratic formula to solve.
=
. Since we need x to be positive (due to it being a side length), our answer is
, because it is the positive option