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
a) 7x + 21 = 0
=> 7x = 0 - 21
=> 7x = -21
=> x = -21 / 7
=> x = -3
Vậy S = { -3 }.
b) 5x - 2 = 0
=> 5x = 0 + 2
=> 5x = 2
=> x = \(\dfrac{2}{5}\)
Vậy S = {\(\dfrac{2}{5}\)}
c) 12 - 6x = 0
=> - 6x = -12
=> x = -12 / (-6)
=> x = 2
Vậy S = { 2 }
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
a.x=3
b.x=1/10
c.x=2
d.x=7
a.x = -3
b.x = 2/5
c.x = -2
d.x = 7