Question

Resolva as equações por favor!!!!

1) x² - x - 20 = 0

2) x² - 3x - 4 = 0

3) x² + 9x + 8 = 0

4) x² - 7x + 5 = 0

5) x² - 5x + 6 = 0

Answer 1

1.-) x^2 - X - 20 = 0

a=1 b=-1. c=- 20

fornula de delta

D = b^2 - 4 a c

D = (-1)^2 - 4 (1) (-20)

D = 1 - 4 (-20)

D = 1 + 80

D = 81

formula de braskara

X = - b + , - \/D
.......________
..............2 a

X = - (- 1) + , - \/81
.......__________
................2 ( 1 )

X = 1 + , - 9
......______
............2

X' = 1 + 9
.......____
...........2

X' = 10
.......___
..........2

X' = 5


X" = 1 - 9
.......____
...........2

X" = - 8
........___
...........2

X" = - 4

S = { - 4 , 5 }

===========================

2.-) X^2 - 3X - 4 = 0

a=1. b=- 3. c=- 4

fornula de delta

D = b^2 - 4 a c

D = (- 3)^2 - 4 (1) (- 4)

D = 9 - 4 (- 4)

D = 9 + 16

D = 25

formula de braskara

X = - b + , - \/D
.......________
...............2a

X = - (- 3) + , - \/25
.......___________
..................2 (1)

X = 3 + , - 5
......_______
..............2

X' = 3 + 5
......_____
...........2

X' = 8
.......__
........2

X' = 4


X" = 3 - 5
........____
............2

X" = - 2
........___
...........2

X" = - 1

S = { - 1 , 4 }

===============================

3.-) X^2 + 9X + 8 = 0

a= 1 b= 9. c= 8

formula de delta

D = b^2 - 4 ( 1 ) (8)

D = ( 9 )^2 - 4 ( 1 ) ( 8 )

D = 81 - 4 ( 8 )

D = 81 - 32

D = 49

formula de braskara

X = - b + , - \/D
.......________
...............2a

X = - (9) + , - \/49
.......__________
.................2 (1)

X = - 9 + , - 7
......._______
...............2

X' = - 9 + 7
........_____
.............2

X' = - 2
........___
...........2

X' = - 1


X" = - 9 - 7
........_____
.............2

X" = - 16
.........___
............2

X" = - 8

S = { - 8 , - 1 }

==============================

4.-) X^2 - 7X + 5 = 0

a= 1. b= - 7 c= 5

formula de delta

D = b^2 - 4 a c

D = (- 7 )^2 - 4 ( 1 )( 5 )

D = 49 - 4 ( 5 )

D = 49 - 20

D = 29

formula de braskara

X = - b + , - \/D
.......________
...............2a

X = - (- 7 ) + , - \/29
.......___________
..................2(1)

X = 7 + , - 5,38
.......________
..............2(1)

X' = 7 + 5,38
......._______
.............2

X' = 12,38
........____
............2

X' = 6,19


X" = 7 - 5,38
........______
..............2

X" = 1,62
........____
............2

X" = 0,81

S = { 0,81 , 6,19 }

=============================

5.-) X^2 - 5X + 6 =0

a= 1. b= - 5 c= 6

formula de delta

D = b^2 - 4 a c

D = (- 5 )^2 - 4 (1) ( 6)

D = 25 - 4 ( 6 )

D = 25 - 24

D = 1


formula de braskara

X = - b + , - \/D
........________
...............2 a

X = - ( - 5 ) + , - \/1
.......__________
................2 (1)

X = 5 + , - 1
......._____
............2

X' = 5 + 1
........____
............2

X' = 6
.......__
. ......2

X' = 3


X" = 5 - 1
........____
.......... .2

X" = 4
........__
.........2

X" = 2

S = { 2 , 3 }