For this case we must find the positive solution of the following quadratic equation:
![x ^ 2-5x-36 = 0](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ws8ll46oh418dtcj4pirc197atabl8vbxc.png)
To find the solutions we factor, that is, we look for two numbers that when multiplied give as result -36 and when summed give as result -5.
These are:
-9 and +4
![-9 * 4 = -36\\-9 + 4 = -5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/27a8lctqxlo29f1hi3qeiu1zsywl5bl9z9.png)
So, we have:
![(x-9) (x + 4) = 0](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6ahesrxymekw0gf623clupkm1p4jm7krbw.png)
The roots are:
![x_ {1} = 9\\x_ {2} = - 4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/jy6bkiktvv23ag08btuidozqxuauq240s0.png)
The positive solution is 9.
Answer:
9