Question

3-Resolva as equações do 2º grau:
a)4x² -36 = 0
b)7x² - 21x = 0
c)x² + 9 = 0
d)x² - 49 = 0
e)5x² - 20 x= 0

Answer 1

Resposta:

a) x² - 7x = 0

x(x-7) = 0, x = 0 ou:

x-7 = 0

x = 7

b)x² +5x = 0

x(x+5) = 0, x = 0 ou:

x + 5 = 0

x = -5

c)4x² - 9x = 0

x(4x-9) = 0, x = 0 ou:

4x - 9 = 0

4x = 9

x = 9/4

d)3x² +5x = 0

x(3x+5) = 0, x = 0 ou:

3x +5 = 0

3x = -5

x = -5/3

e)4x²-12x = 0

4x(x-3) = 0, x = 0 ou:

x -3 = 0

x = 3

f)5x²+x = 0

x(5x+1) = 0, x = 0 ou:

5x + 1 = 0

5x = -1

x = -1/5

g)x²+x = 0

x(x+1) = 0, x = 0 ou:

x + 1 = 0

x = -1

h)7x²-x = 0

x(7x-1) = 0, x = 0 ou:

7x -1 = 0

7x = 1

x = 1/7

i)2x² = 7x

2x²-7x = 0

x(2x - 7) = 0, x = 0 ou:

2x -7 = 0

x = 7/2

j)2x² = 8x

2x² -8x = 0

2x(x-4) = 0, x = 0 ou:

x - 4 = 0

x = 4

k)7x² = -14x

7x² +14x = 0

7x(x+2) = 0, x = 0 ou:

x + 2 = 0

x = -2

1) -2x² +10x = 0

-2x(x+5) = 0, x = 0 ou:

x + 5 = 0

x = -5