We can use the quadratic equation to solve this problem:
The quadratic formula states:
For color(red)(a)x^2 + color(blue)(b)x + color(green)(c) = 0, the values of x which are the solutions to the equation are given by:
x = (-color(blue)(b) +- sqrt(color(blue)(b)^2 - (4color(red)(a)color(green)(c))))/(2 * color(red)(a))
Substituting:
color(red)(-16) for color(red)(a)
color(blue)(5) for color(blue)(b)
color(green)(30) for color(green)(c) gives:
x = (-color(blue)(5) +- sqrt(color(blue)(5)^2 - (4 * color(red)(-16) * color(green)(30))))/(2 * color(red)(-16))
x = (-color(blue)(5) +- sqrt(25 - (-1920)))/-32
x = (-color(blue)(5) +- sqrt(25 + 1920))/-32
x = (-color(blue)(5) +- sqrt(1945))/-32
x = (color(blue)(5) +- sqrt(1945))/32