Question

Resolva as equações do 2 grau:

(a) x²-5x=0

(b) -x²+12x=0

(c) x² -9x=0

(d) x²-9=0

(e) 25x²-1=0

Answer 1

(a) x² - 5x = 0
x • (x - 5) = 0
x =0 ou x = + 5

(b) - x² + 12x = 0
- x • (x - 12) = 0
x = 0 ou x = 12

(c) x² - 9x = 0
x • (x - 9x ) = 0
x = 0 ou x = 9

(d) x² - 9 = 0
x² = 0 + 9
x² = 9
x = ±√9
x = ±3
x = 3 ou x = - 3

(e) 25x² - 1 = 0
25x² = 0 + 1
25x² = 1
x = ±√1 / 25
x = ± 1 / 5

x = + 1/5 ou x= -1/5

Answer 2

Olá...

a) x² - 5x = 0

x(x - 5) = 0

x' = 0

x - 5 = 0

x = 5

S = [0, 5]

b) - x² + 12x = 0

x( - x + 12) = 0

x' = 0

- x + 12 = 0

- x = - 12 →(× por -1)

x" = 12

S = [0, 12]

c) x² - 9x = 0

x(x - 9) = 0

x' = 0

x - 9 = 0

x" = 9

S = [0,9]

d) x² - 9 = 0

x² = 9

x = ± √9

x = ± 3

S = [3, - 3]

e) 25x² - 1 = 0

25x² = 1

x² = 1/25

x = ± $\sqrt{\frac{1}{25} }$

x = ± $\frac{1}{5}$

$S=[\frac{1}{5},-\frac{1}{5}]$

Espero ter ajudado.