-x² + 5x + 9 = 0
On comparing this equation to: ax²+bx+c= 0
We get, a = -1; b = 5; c = 9
Solving by quadratic formula,
x = [-b ± √(b²-4ac)]/2a
=> x = [-5 ± √{5²-4(-1)(9)}]/2(-1)
=> x = [-5 ± √(25-(-36)]/-2
=> x = [-5 ± √(25+36)]/-2
=> x = [-5 ± √61]/-2
=> x = [-5 + √61]/-2 or [-5 - √61]/-2
=> x = (-5/-2) + (√61/-2) or (-5/-2) + (-√61/-2)
=> x = (5/2) + (-√61/2) or (5/2) + (√61/2)
So, x = (5/2) + (-√61/2) or (5/2) + (√61/2)
