How do you find the roots, real and imaginary, of y= 12x^2 + 35x + 72 using the quadratic formula?

1 Answer
Feb 13, 2018

x = -35/24+-sqrt(2231)/24i

Explanation:

The equation:

y = 12x^2+35x+72

is a quadratic in standard form:

y = ax^2+bx+c

with a=12, b=35 and c=72

It has zeros given by the quadratic formula:

x = (-b+-sqrt(b^2-4ac))/(2a)

color(white)(x) = (-(color(blue)(35))+-sqrt((color(blue)(35))^2-4(color(blue)(12))(color(blue)(72))))/(2(color(blue)(12)))

color(white)(x) = (-35+-sqrt(1225-3456))/24

color(white)(x) = (-35+-sqrt(-2231))/24

color(white)(x) = -35/24+-sqrt(2231)/24i

Note that 2231 = 23 * 97 has no square factors, so sqrt(2231) cannot be simplified.