Question

Answer 1

Bài 14: 

a:=>7x=-21

hay x=-3

b: =>5x=2

hay x=2/5

c: =>6x=12

hay x=2

d: =>-2x=-14

hay x=7

Answer 2

14.
a, \(7x+21=0\Leftrightarrow7x=-21\Leftrightarrow x=3\)
b, \(5x-2=0\Leftrightarrow5x=2\Leftrightarrow x=\dfrac{2}{5}\)
c, \(12-6x=0\Leftrightarrow6x=12\Leftrightarrow x=2\)
d, \(-2x+14=0\Leftrightarrow-2x=-14\Leftrightarrow x=7\)
 

Answer 3

14.a.7x+21=0

⇔7x=-21 ⇔ x=-3

b.5x-2=0

⇔5x=2

⇔x=\(\dfrac{2}{5}\)

c.12-6x=0

⇔6x=12

⇔x=2

d.-2x+14=0

⇔-2x=-14

⇔x=7