Bonjour, voici mon probleme: factoriser 5(x+0,2)au carré -3,2 Merci

bonjour

5(x-0.2)²-3.2

5(x²-0.4x+0.04)-3.2

5x²-2x+0.2-3.2

5x²-2x-3

Δ=2²-4(5)(-3)

Δ=4+60

Δ=64

√Δ=8

x1=2+8/10 x1=10/10=1

x2=2-8/10=-6/10 x2=-0.6

d'où

factorisation

5(x-1)(x+0.6)

5(x+0.2)²-3.2=5(x+0.6)(x-1)