x = about 1 or x = about -2
9x^2 + 12x - 24 is standard form: ax^2 + bx + c
quadratic formula: x = (-b ± √(b^2 - 4ac)) / 2a
x = -12 ± √(12^2 - 4(9)(-24)) / 2(9)
x = -12 ± √(144 - (-864) / 18
x = -12 ± √(144 + 864) / 18
x = -12 ± √(1008) / 18
x = -12 ± √(1008) / 18
x = −2 ± 2√7/3
x = -2 + 2√7/3 or x = -2 - 2√7/3
x = 1.0971675407097272 or x = −2.4305008740430605