f(x) = 0, where

f(x) = -5x2 + 8x + 9

2 answers

just use your normal methods to solve quadratic equations:

-5x^2+8x+9 = 0

I don't see any easy way to factor that, so try the quadratic formula or completing the square.
In google type :

quadratic equation online

When you see list of results click on:

Free Online Quadratic Equation Solver: Solve by Quadratic...

When page be open in rectanlgle type:

-5 x ^ 2 + 8x + 9 = 0

and click option :

solve it!

You will see solution step - by - tep