1. Professor de Matemática no Colégio Estadual Dinah Gonçalves
E Biologia na rede privada de Salvador-Bahia
Professor Antonio Carlos carneiro Barroso
email accbarroso@hotmail.com
Blog HTTP://ensinodematemtica.blogspot.com
Equações de 2º grau Completa:
−b+ ∆ −b
xi = e x i + x ii =
− b± ∆ 2a a
x= −b− ∆ c
2a x ii =
2a
x .x ii =
a
Resolvendo:
x2 − x + =
5 6 0
a =1
b = 5
−
c =6
∆ b 2 − ac
= 4
∆ (− )
2
= 5 − .1 .6 =
4 25 −24 =1
− ± ∆
b
x =
2a
−− ) ± 1
( 5
x =
2 .1
5± 1
x =
2
i 5 + 1 6
x = = 3
2 2
5− 1 4
x ii = = = 2
2 2
S = 2,3)
(

2. x2 − + =
8x 15 0
a =1
b =−
8
c =
15
∆b 2 −
= 4 ac
∆ ( 8 ) − 1.15 =
2
= − 4.
∆ 64 − =
= 60 4
−±∆
b
x =
2a
− 8 )±4
(−
x =
2.1
8 ± 2
x =
2
8 + 2 10
xi = = =5
2 2
8 − 2 6
x ii = = = 3
2 2
S = ,5 )
(3
X2-4x+4=0
▲=b2-4ac
▲=42-4.1.4=16-16=0
− ( − 4) ± 0
4±0 4+0 4 4−0 4
X= 2.1 x= x1 = = =2 x2 = = =2
2 2 2 2 2
S = ( 2)
x 2 + 2 x +1 = 0
−b  ∆ − ( + 2) ± 0
∆ = b 2 − 4ac x= x=
2a 2.1
∆ = ( 2 ) − 4.1.1 = 4 − 4 = 0
2
−2 +0 −2
x1 = = = −1
2
−2 −0 −2
2
S = ( − 1)
x2 = = = −1
2 2

3. x 2 −4 x + =0
5
a = , b =− , c =5
1 4
∆=b 2 −4ac
∆=(−4 )
2
− .1.5 =
4 16 −20 =−4
∆0
〈
S =[ ]
x 2 −4 x − =0
5
a = , b =− , c =−
1 4 5
∆=b 2 −4ac
∆=(−4 ) −4.1.(− ) =
5 16 +20 =36
− ± ∆
b
x =
2a
−(−4 ) ± 36 4 ±6
x = =
2 .1 2
4 +6 10
x = = =5
2 2
4 −6 −2
x = = =− 1
2 2
S =(− ,5)
1
4x −4 x + =0
1
a =4, b =− , c =1
4
∆=b 2 −4ac =( −4 ) −4.4.1 =16 −
2
16 =0
−b ± ∆ −( −4 ) ± 0 4 ±0 4 1
x = = = = =
2a 2.4 8 8 2
1 
S = 
2 

4. x 2 − x + = → = 2,3)
5 6 0 S (
x 2 − x + = → = 1,5 )
6 5 0 S (
x 2 − x − = → = − ,3)
2 3 0 S ( 1
x 2 − x − = → = − ,5 )
4 5 0 S ( 1
x 2 − x + = → = 1,6 )
7 6 0 S (
x2 − x +
7 10 = → = 2,5 )
0 S (
x 2 + x + = → = − ,− )
7 6 0 S ( 1 6
x2 − x + = → =
4 6 0 S [ ]
x 2 − x + = → = 1,2 )
3 2 0 S (
x 2 + x + = → (− ,− )
3 2 0 S 1 2
x 2 − x + = → = 2)
4 4 0 S (
x2 − x +
8 15 = → = 3,5)
0 S (
x2 − x +
9 14 = → = 2,7 )
0 S (
x2 −10 +25 = → = 5 )
0 S (
x2 + x +
11 30 = → = − ,− )
0 S ( 5 6
− 2 + x+
x 3 10 = → = 2,5)
0 S (
 4
3 x 2 − x + = → = 1, 
7 4 0 S 
 3
x2 + x −
4 21 = → = 3,− )
0 S ( 7
x2 + x +
8 16 = → = − )
0 S ( 4
3x 2 − x +
2 24 = → =
0 S [ ]
x2 − x +
10 24 = → = 4,6 )
0 S (
x 2 − x + = → = 1,3)
4 3 0 S (
x2 − x −
4 12 = → = − ,6 )
0 S ( 2
Professor Antonio Carlos Carneiro Barroso