Question

Giải các phương trình sau :

a) \(7x+21=0\)

b) \(5x-2=0\)

c) \(12-6x=0\)

d) \(-2x+14=0\)

Answer 1

a,7x+21=0

<=>7x=-21

<=>x=-3

b,5x-2=0

<=>5x=2

<=>x=2/5

c,12-6x=0

<=>-6x=-12

<=>x=2

d,-2x+14=0

<=>-2x=-14

<=>x=7

Answer 2

a) 7x + 21 = 0

=> 7x = 0 - 21

=> 7x = -21

=> x = -21 / 7

=> x = -3

Vậy S = { -3 }.

Answer 3

b) 5x - 2 = 0

=> 5x = 0 + 2

=> 5x = 2

=> x = \(\dfrac{2}{5}\)

Vậy S = {\(\dfrac{2}{5}\)}

Answer 4

c) 12 - 6x = 0

=> - 6x = -12

=> x = -12 / (-6)

=> x = 2

Vậy S = { 2 }

Answer 5

a, 7x+21=0

<=>7x=-21

<=>x=-3

b, 5x-2=0

=>5x=2

=>x=2/5

c,12-6x=0

=>-6x=12

=>x=-2

d,-2x+14=0

=>-2x=-14

=>x=7

Answer 6

a.x=-3

b.x=2/5

c.x=2

d.x=7

Answer 7

a.x=3

b.x=1/10

c.x=2

d.x=7

Answer 8

a.x = -3

b.x = 2/5

c.x = -2

d.x = 7