Question

Resolva as equações do 2.0 grau, sendo U= R
U = R:
a) x2 - 9 = 0
b) 4x2 - 25 = 0
c) 9x²=49
d) x²-2=0
e) 8x²-320=0
f) -x²+ 2x=0
g)x²-15x=0
h) 5x²+×=0
i) 4x²-36x=0 ​

Answer 1

a) x² - 9 = 0

x²= 9

x= ± √9

x= ± 3

S= ( 3 , - 3)

b) 4x² - 25 = 0

4x²= 25

x²= 25/4

x= ± √25/4

x= ± 5/2

S= ( 5/2 , - 5/2)

c) 9x²=49

x²= 49/9

x= ± √49/9

x= ± 7/3

S= ( 7/3 , - 7/3)

d) x²-2=0

x²= 2

x= ± √2

S= ( √2 , - √2)

e) 8x²-320=0

8x²= 320

x²= 320/8

x²= 40

x= ± √40

S= ( √40 , - √40)

f) -x²+ 2x=0

x • ( -x + 2) = 0

x= 0

- x + 2 = 0

- x = - 2(-1)

x= 2

S= ( 0 , 2)

g)x²-15x=0

x • (x - 15)= 0

x= 0

x - 15 = 0

x= 15

S= ( 0 , 15)

h) 5x²+ x= 0

x • ( 5x + 1) = 0

x= 0

5x + 1 = 0

5x= - 1

x= - 1/5

x= - 0,2

S= ( 0 , - 0,2)

i) 4x²-36x=0

x • (4x - 36) = 0

x= 0

4x - 36= 0

4x= 36

x= 36/4

x= 9

S= ( 0, 9)