Tentukan akar persamaan kuadrat x^2 + 7x-9=0 dengan menggunakan rumus abc(kuadrat)

x² + 7x - 9 = 0
a = 1. b = 7. c = -9

X12 = (-b ± √b² - 4ac ) / 2a
X12 = (-7 ± √7² - 4(1)(-9)) / 2(1)
X12 = (-7 ± √49 + 36) / 2
X12 = (-7 ± √81) / 2
X12 = (-7 ± 9) / 2

X1 = (-7 + 9) / 2 = 2/2 = 1
X2 = (-7 - 9) / 2 = -16 / 2 = -8