Question

Resolva as eq de 2° grau
a) x²-22-2=0
b)x²-324=0
c)-2x²+162=0
d)3x²+12x=0
e)-5x²-7x=0
f)2x=8x²
g)2x²+x=1​

Answer 1

Resposta:

Olá bom dia!

a) x²-22-2=0

x² -24 = 0

x² = 24

x = ±√24 = ±√(4.6) = ±2√6

b)x²-324=0

x² = 324

x = √324 =

x = ±18

c)-2x²+162=0

-2x² = -162

2x² = 162

x² = 162 : 2

x² = 81

x = √81

x = ±9

d)3x²+12x=0

x (3x + 12) = 0

x = 0

3x + 12 = 0

3x = - 12

x = -12 : 3

x = -4

e)-5x²-7x=0

x (-5x - 7) = 0

x = 0

-5x - 7 = 0

5x + 7 = 0

5x = -7

x = -7/5

f)2x=8x²

8x² - 2x = 0

x (8x - 2) = 0

x = 0

8x - 2 = 0

8x = 2

x = 2/8

x = 1/4

g)2x²+x=1​

2x² + x - 1 = 0

a = 2

b = 1

c = -1

Δ = b² - 4ac

Δ = 1² - 4(2)(-1)

Δ = 1 + 8

Δ = 9

√Δ = √9 = 3

x = (-b ± √Δ) : 2a

x = (-1 ± 3) : 2(2)

x' = 2 : 4

x' = 1/2

x" = -4 : 4

x" = -1