Bài 6:

a) 2.(-25).(-4).50

= 2.50.(-25).(-4)

= 100.100

= 10 000

b) (-125).5.(-16).(-8)

= (-125).(-8).5.(-16)

= 1000.(-80)

= -80 000

c) (-5)².(-3)³.2³

= 25.(-27).8

= 25.8.(-27)

= 200.(-27)

= -5400

d) -(-4²).3².(-5)³

= 16.9.(-125)

= 16.(-125).9

= -2000.9

= -18 000

e) 124+(-52).124+(-124).(-47)

= 124.[1+(-52)+47]

= 124.(-4)

= -496

f) -55.78+13.(-78)-78.(-65)

= 78.(-55-13+65)

= 78.(-3)

= -234

g) -134+51.134+(-134).48

= 134.(-1+51-48)

= 134.2

= 268

Bài 7:

a) 3-x=15-(-5)

⇔ 3-x=20

⇔ x=-17

Vậy S={-17}

b) -x-14+32=-26

⇔ -x+18=-26

⇔ x=44

Vậy S={44}

c) x+(-31)-(-42)=-45

⇔ x = -45+31-42

⇔ x = -56

Vậy S={-56}

d) -12-(13-x)=-15-(-17)

⇔ -13+x=-15+17+12

⇔ -13+x=14

⇔ x = 27

Vậy S={27}

e) x-43=(35-x)-48

⇔ x+x=43+35-48

⇔ 2x=30

⇔ x=15

Vậy S={15}

f) 305-x+14=48+(x-23)

⇔ -x-x=48-23-14-305

⇔ -2x=-294

⇔ x=147

Vật S={147}

g) -(x-6+85)=(x+51)-54

⇔ -x+6-85=x+51-54

⇔ -x-x=51-54-6+85

⇔ -2x=76

⇔ x=-38

Vậy S={-38}

h) -(35-x)-(37-x)=33-x

⇔ -35+x-37+x=33-x

⇔ x+x+x=33+37+35

⇔ 3x = 105

⇔ x = 35

Vậy S={35}

Bài 8:

a) 13-|x|=|-4|

⇔ 13-|x|=4

⇔ |x|=9

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

Vậy S={-9;9}

b) |x-15|+6=16

⇔ |x-15| = 10

⇔ \(\left[ \begin{array}{l}x-15=10\\x-15=-10\end{array} \right.\)

⇔ \(\left[ \begin{array}{l}x=25\\x=5\end{array} \right.\)

Vậy S={25;5}

c) 35-|2x-1|=14

⇔ |2x-1|=21

⇔ \(\left[ \begin{array}{l}2x-1=21\\2x-1=-21\end{array} \right.\)

⇔ \(\left[ \begin{array}{l}x=11\\x=-10\end{array} \right.\)

Vậy S={11;-10}

d) 2.|25-x|-45=-23

⇔ 2.|25-x|=22

⇔ |25-x|=11

⇔ \(\left[ \begin{array}{l}25-x=11\\25-x=-11\end{array} \right.\)

⇔ \(\left[ \begin{array}{l}x=14\\x=36\end{array} \right.\)

Vậy S={14;36}

Bài 9: