Question

Solve the equation -x^2+5x+9=0

Answer 1

-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)