Página 14

A)
x² + 2.10x +100 = 400

(x + 10)² = 400
(x + 10)² = √400
x + 10 = 20
x = 20 - 10
x = 10

B)
x² + 2.2,5x + 6,25 = 12,25

(x + 2,5)² = 12,25
x + 2,5 = √12,25
x + 2,5 =3,5
x = 3,5 - 2,5
x = 1

C)
x² + 2.1x + 1 = -1 + 1
x² + 2x +1 = 0

(x + 1)² =0
x + 1 = √0
x + 1 = 0
x = -1