Question

Formula Bhaskara.
x²-9x-9=0

Answer 1

x² - 9x - 9 = 0

a = 1
b = - 9 
c = - 9

Δ = b² - 4.a.c
Δ = ( - 9)² - 4 . 1 . ( - 9)
Δ = 81 + 36
Δ = 117

x = - b + - √Δ/2a
x = - ( - 9) + - √117/2.1
x = 9 + - 10,816654/2

x' = 9 - 10,816654/2 ⇒ x' = - 1,816654/2 ⇒ x' = - 0,908327 ⇒ x' = ≈ - 0,91
x" = 9 + 10,816654/2 ⇒ x" = 19,816654/2 ⇒ x" = 9,908327⇒ x" = ≈ 9,91

S = {  - 0,91 e  9,91 }