Question

x² +x -90 =0 quais as raízes?

Answer 1

x² +x -90 =0

a= 1
b = 1
c = -90

Δ = b² -4 .a .c
Δ = 1² -4 . 1 . -90
Δ = 1 + 360
Δ = 361

-b +- √ Δ     /2.a
-1 +- √361   / 2 .1
-1 +- 19   / 2

x' = -1 + 19  /2 
x' = 18 / 2
x' =9

x" = -1 - 19   /2
x" = -20 / 2
x" = -10

Resposta: S:{ 9  e  -10}

Answer 2

Δ = b² - 4ac
Δ = 1² - 4.1.(-90)
Δ = 1 - 360
Δ = 361

X = (-b +/- √Δ)/2a
X = (-1 +/- 19)/2
Xi = (-1+19)/2
xi = 9

Xii = (-1-19)/2
Xii = -10

S {9,-10}