Question

X² -x -20 = 0
resolva essa equação por favor

Answer 1

X² -x -20 = 0 
a= 1 b=-1 c=-20

Δ = b² -4 .a .c
Δ = (-1)² -4 . 1 .(-20) 
Δ = 1 +80
Δ =81

x= -b + - √Δ/2a
x = - (-1) + - √81/2.1
x = 1 +-9/2

x' = 1+9/2 = 10/2 = 5

x" = 1 -9/2
x" = -8 /2 
x" = -4

S = {-4;5}