Question

URGENTE!!!
RESOLVA AS EQUAÇÕES COMPLETAS
a)2x²+7x+5=0
b)x²+5x-14=0 ​

Answer 1

a) 2x² + 7x + 5 = 0

a = 2

b = 7

c = 5

∆ = b² - 4 . a . c

∆ = 7² - 4 . 2 . 5

∆ = 49 - 40

∆ = 9

x = - b ± √∆

------------

2a

x' = - 7 - 3

----------

2 . 2

x' = - 10 (÷2)

---

4 (÷2)

x' = - 5

--- ou - 2,5

2

x" = - 7 + 3

----------

2 . 2

x" = - 4

---

4

x" = - 1

S = {(-5/2 , -1)}

b) x² + 5x - 14 = 0

a = 1

b = 5

c = - 14

∆ = b² - 4 . a . c

∆ = 5² - 4 . 1 . (-14)

∆ = 25 + 56

∆ = 81

x = - b ± √∆

------------

2a

x' = - 5 - 9

----------

2 . 1

x' = - 14

-----

2

x' = - 7

x" = - 5 + 9

----------

2 . 1

x" = 4

---

2

x" = 2

S = {(-7 , 2)}