What are the zeros of the quadratic function f (x) = 2x2 + 16x - 9?

Use the quadratic formula

a = 2 b = 16 c = - 9

x = [-b + - sq root (b^2 - 4*a*c) ] / 2*a

x = [-16 + - sq root (256 - 4*-18) ] / 4

x = [-16 + - sq root (256 + 72) ] / 4

x = (-16 + - 18.11) / 4

x1 =.5275

x2 = - 8.5275