a, 4¹⁰. 2³⁰=2²⁰.2³⁰=2⁵⁰

b,9²⁵.27⁴.81³= 3⁵⁰.3¹².3¹²=3⁷⁴

Tương tự các câu khác....

a, 4¹⁰.2³⁰ = (2²)¹⁰.2³⁰ = 2²⁰.2³⁰ = 2⁵⁰
b, 9²⁵.27⁴.81³ = (3²)²⁵.(3³)⁴.(3⁴)³ = 3⁵⁰.3¹².3¹² = 3⁷⁴
c, 25⁵⁰.125⁵ = (5²)⁵⁰.(5³)⁵ = 5¹⁰⁰.5¹⁵ = 5¹¹⁵
d, 64³.4⁸.16⁴ = (2⁶)³.(2²)⁸.(2⁴)⁴ = 2¹⁸.2¹⁶.2¹⁶ = 2⁵⁰
e, 3⁸ : 3⁶ = 3²
2¹⁰ : 8³ = 2¹⁰ : (2³)³ = 2¹⁰ : 2⁹ = 2
12⁷ : 6⁷ = (12 : 6)⁷ = 2⁷
@Dương Tuyết Mai

lần lượt là:3920

6000

5600

6100

(x + 2) + (x + 5) +(x + 7) +(x + 12) + (x + 19) + (x + 31) + (x + 50) + (x + 81) + (x + 131) = 347

8x+(2+5+7+12+19+31+50+81+131)=347

8x+338=347

8x=9

Vậy =9/8

chúc bạn học tốt ^-^

Vì   (x+2)+(x+5)+(x+7)+(x+12)+.............+(x+81)+(x+131)=347 

\(\Rightarrow\)(x+2)+(x+5)+(x+2+5)+(x+5+7)+(x+ 7+12)+(x+12+19)+(x+19+31)+(x+50+81)=347 

\(\Rightarrow\)9x+2+5+7+12+19+31+50+81+131=347

\(\Rightarrow\)9x+362=347

\(\Rightarrow\)9x=347-362=-15

\(\Rightarrow\)x=15:9=\(\frac{5}{3}\)

Vậyx=\(\frac{5}{3}\)

x=5/3

32 x 50 / 48 x 75 = 1600 / 3600 = 4/9

63 x 81 / 135 x 84 = 5103 / 11340 = 9/20

1111 x 5 / 7 x 1515 = 5555 / 10605 = 11/21 

Chúc bạn học tốt !!!

a) 84

b) -300

c) 1700

a) = 10 . ( 7.8 )

= 10 . 56 

= 560 

b) 

= 9.2.7.5

= ( 9.7 ) . ( 2.5 )

= 63 . 10 

= 630 

b) 7.x=42

x = 42 : 7 

x = 6

c) 180 : x = -12

x = 180 : ( -12 )

x = -15

b,84  c,-300  d,1700

a,=560  b,=630  

b)(-12).(-7)=84

c)15.(-20)=-300

D)34.50=1700

a)7.2.5.8

=2.5.7.8

=10.56

=560

b)9.2.(-7).(-5)

=2.(-5).9.(-7)

=(-10).(-63)

=630

b)7.x=42

      X=42:7

      X=6

c)180:x=-12

           x=180:(-12)

           x=-15

Bài 1:

a; (\(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\)) x \(\dfrac{3}{4}\) = \(\dfrac{1}{4}\)

     \(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) : \(\dfrac{3}{4}\)

      \(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) x \(\dfrac{4}{3}\)

    \(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) =  \(\dfrac{1}{3}\)

      \(\dfrac{1}{4}x\) = \(\dfrac{1}{3}\) + \(\dfrac{1}{8}\)

       \(\dfrac{1}{4}\) \(x\)=  \(\dfrac{8}{24}\) + \(\dfrac{11}{24}\)

          \(\dfrac{1}{4}x=\dfrac{11}{24}\)

           \(x=\dfrac{11}{24}:\dfrac{1}{4}\)

           \(x=\dfrac{11}{24}\times4\)

           \(x=\dfrac{11}{6}\) 

b; \(\dfrac{12}{5}:x\) = \(\dfrac{14}{3}\) x \(\dfrac{4}{7}\)

     \(\dfrac{12}{5}\) : \(x\) = \(\dfrac{8}{3}\)

            \(x\) = \(\dfrac{12}{5}\) : \(\dfrac{8}{3}\)

            \(x\) = \(\dfrac{12}{5}\) x \(\dfrac{3}{8}\)

             \(x\) = \(\dfrac{9}{10}\)

c; \(x+\dfrac{2}{3}\) = 8:4 - 1

   \(x+\dfrac{2}{3}\) = 2 - 1

   \(x+\dfrac{2}{3}\) = 1

  \(x=1-\dfrac{2}{3}\)

  \(x\) = \(\dfrac{1}{3}\)

Hướng dẫn giải:

a) 71 x 5 x 4 = 71 x (5 x 4) = 71 x 20 = 1420

b) 123 x 50 x 2 = 123 x (50 x 2) = 123 x 100 = 12300

c) 4 x 138 x 25 = (4 x 25) x 138 = 100 x 138 = 13800

d) 25 x 96 x 4 = (25 x 4) x 96 = 100 x 96 = 9600

e) 5 x 81 x 2 = (5 x 2) x 81 = 10 x 81 = 810

g) 50 x 104 x 2 = (50 x 2) x 104 = 100 x 104 = 10400