Respostas

2014-08-05T20:50:23-03:00
Olá, ALINE0000!

a) 2x² - 9x + 4 = 0
a = 2
b = -9
c = 4

Δ = b² - 4.a.c
Δ = (-9)² - 4.2.4
Δ = 81 - 32
Δ = 49

-b +- √Δ / 2.a
-(-9) +- √49 / 2.2
9 +- 7 / 4

x' = 9+7/4 = 16/4 = 4
x'' = 9-7/4 = 2:2/4:2 = 1/2

b) 25x² - 20x + 4 = 0
a = 25
b = -20
c = 4

Δ = b² - 4.a.c
Δ = (-20)² - 4.25.4
Δ = 400 - 400
Δ = 0

-b / 2a
-(-20) / 2.25
20:10 / 50:10
2/5

c) 4x² - 9x + 9 = 0
a = 4
b = -9
c = 9

Δ = b² - 4.a.c
Δ = (-9)² - 4.4.9
Δ = 81 - 144
Δ = -63
1 4 1