Question

qual e a raizes dessa equação x²-x-20=0

Answer 1

Δ = b² -4.a.c
Δ = (-1)² -4.1.(-20)
Δ = 1 + 80
Δ = 81


x = -b ±√Δ / 2a
x = -(-1) ± 9 / 2
x = 1 ± 9 / 2

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

x'' = 1 - 9 /2
x'' = -8 /2
x''= -4

Answer 2

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 

-b +- √Δ / 2*a
-b +- √81 /2*a
-b +- 9 /2*a

x' = $\frac{-(-1) + 9}{2*1}$
x' = $\frac{1 + 9}{2}$
x' = $\frac{10}{2}$
x' = 5

x'' = $\frac{-(-1) - 9}{2*1}$
x'' = $\frac{1 - 9}{2}$
x'' = $\frac{-8}{2}$
x'' = -4

S{ 5 e -4}