a,|x+2|=0

⇔x+2=0

⇔x=0

b,128-3(x+4)=23

⇔3(x+4)=105

⇔x+4=35

⇔x=31

c, [(6x - 39) : 7 ] . 4 =12

⇔(6x-39):7=3

⇔6x-39=21

⇔6x=60

⇔x=10

d, ( x : 3 - 4 ) . 5 = 15

⇔x:3-4=3

⇔x:3=7

⇔x=21

e, ( 7 - x ) - ( 25 + 7 ) = -25

⇔(7-x )-32=-25

⇔7-x=7

⇔x=0

g, ( 3x - $2^{4}$ ) . 7³ = 2.$7^{4}$ 

⇔(3x-16).343=2.2401

⇔(3x-16).343=4802

⇔3x-16=14

⇔3x=30

⇔x=10

h, x - [ 42 +( -28 ) ] = -8

⇔x-14=-8

⇔x=6

i,|x-3| = |5| + |-7|

⇔|x-3|=12

⇔\(\left[ \begin{array}{l}x-3=12\\x-3=-12\end{array} \right.\) 

⇔\(\left[ \begin{array}{l}x=15\\x=-9\end{array} \right.\) 

k, 4 - ( 7-x ) = x - ( 13 - 4 )

⇔4-7+x=x-9

⇔-3+x=-9+x

⇔ x∈∅ ( x thuộc rỗng)

~ học tốt ~

 

a, |7 + 2| = 0

b, 128 - 3 .(2+4) = 23

c, [(67 - 39) : 7 ] . 4 =12

d, ( 5 : 3 - 4 ) . 5 = 15

e, ( 7 - 3 ) - ( 25 + 7 ) = -25

g, ( 35 - 2^4 ) . 7^3 = 2 . 7^4

h, 4 - [ 42 +( -28 ) ] = -8

i,|2-3| = |5| + |-7|

k, 4 - ( 7-x ) = 4 - ( 13 - 4 )