How would you solve this? -b²+8b-10=0

The first step to solve this problem is to add 10 to both sides. 
Now you would get -b^2 + 8b = 10
The next step is dividing 8 to both sides 
Now you would get -b^2 + b = 1.25
Next, you now know that you have a exponent squared. So, the next step is to get rid of the ^2 and take 1.25 and square root that to get 1.12
So now, you would have -b + b =1.12 
Because -b + b is 0, there is no valid answer