Question

como resolver 20a³-2a²-4a=0

Answer 1

a(20a² - 2a - 4) = 0
a = 0 ou 20a² -2a - 4 = 0
10a² - a - 2 = 0
Δ = (-1)² - 4.10.(-2)
Δ = 1 + 80
Δ = 81
a = (1- 9)/10 = -8/20 = -2/5 ou
a = (1 + 9)/20 = 10/20 = 1/2
S ={-2/5, 0, 1/2}