First, rearrange the quadratic equation:
5x² + 9x - 4 = 0
Now, compare it to the general quadratic equation:
ax² + bx + c = 0
Therefore you get:
a = +5
b = +9
c = -4
And the quadratic formula will be:
x = [-b +/- √(b² - 4ac)] / 2a
= [ -5 +/- √(81 - 4·5·(-4))] / 2·5
= (-5 +/- √161) / 10
