a = -16 b = 0 c = 541
Use the quadratic formula which is 
x = [-b +- sq root (b^2 -4*a*c)] / 2*a
x = [-0 +-sq root (0 -4*-16*541)] / 2 * -16
x = + - sq root (0 -4*-16*541) / -32
x = + - sq root (34,624) / -32
x = + - 186.075 / -32
x1 = 186.075 / -32 =    -5.81484375    
x2 = -186.075 / -32 =    5.81484375