Answer:
x=2 or x=-4. You can also write it as x=2,-4
Explanation:
Write your equation and start by subtracting 9 from both sides
10x^2+20x-71-9=9-9
You should end up with
10x^2+20x-80=0
For this equation: a=10, b=20, c=-80
Now we use the quadratic formula and substitute the information. I have attached a picture for you.