Học sinh nhẩm và ghi:

8 x 5 = 40

8 x 4 = 32

8 x 6 = 48

8 x 3 = 24

40 : 8 = 5

32 : 8 = 4

48 : 8 = 6

24 : 8 = 3

40 : 5 = 8

32 : 4 = 8

48 : 6 = 8

24 : 3 = 8

(chú ý: mối quan hệ giữa nhân và chia)

Tính nhẩm:

8 x 5 = 40

8 x 4 = 32

8 x 6 = 48

8 x 3 = 24

40 : 8 = 5

32 : 8 = 4

48 : 8 = 6

24 : 8 = 3

40 : 5 = 8

32 : 4 = 8

48 : 6 = 8

24 : 3 = 8

k cho mik với

đề bài là làm gì vậy bạn?

Tính m x n nhé bạn

x.2³² = 8¹¹

x.2³² = (2³)¹¹

x.2³² = 2³³

x = 2³³:2³²

x = 2

2^x+1:8 = 32⁵

2^x+1 = 32⁵.8

2^x+1 = (2⁵)⁵.2³

2^x+1 = 2²⁵.2³

2^x+1 = 2²⁸

=> x + 1 = 28

=> x = 28 - 1 = 27

x.2³² = 8¹¹

x .2³² =(2³ )¹¹

x.2³² = 2³³

x = 2³³ : 2³²

x = 2

2^x+1:8=32⁵

2^x+1=32⁵ x 8

2^x+1= ( 2⁵ )⁵ x 2³

2^x+1 = 2²⁵ x 2³

2^x+1 = 2²⁸

x + 1 = 28

x = 28 - 1

x = 27

x.2³² = 8¹¹

x.2³² = (2³)¹¹

x.2³² = 2³³

x = 2³³:2³²

x = 2

2^x+1:8 = 32⁵

2^x+1 = 32⁵.8

2^x+1 = (2⁵)⁵.2³

2^x+1 = 2²⁵.2³

2^x+1 = 2²⁸

=> x + 1 = 28

=> x = 28 - 1 = 27

1. \(x-8+32=68\)

\(x-8=68-32\)

\(x-8=36\)

\(x=36+8\)

\(x=44\)

_____

2. \(x+8+32=68\)

\(x+8=68-32\)

\(x+8=36\)

\(x=36-8\)

\(x=28\)

_____

3. \(98-x+34=43\)

\(98-x=43-34\)

\(98-x=9\)

\(x=98-9\)

\(x=89\)

_____

4. \(98+x-34=43\)

\(98+x=43+34\)

\(98+x=77\)

\(x=77-98\)

\(x=-21\)

_____

5. \(x:5:4=800\)

\(x:5=800.4\)

\(x:5=3200\)

\(x=3200.5\)

\(x=16000\)

_____

6. \(18+x=384:8\)

\(18+x=48\)

\(x=48-18\)

\(x=30\)

_____

7. \(\left(84,6-2\times x\right):3,02=5,1\)

\(84,6-2.x=5,1.3,02\)

\(84,6-2.x=15,402\)

\(2.x=84,6-15,402\)

\(2.x=69,198\)

\(x=69,198:2\)

\(x=34,599\)

_____

8. \(x\times5=120:6\)

\(x.5=20\)

\(x=20:5\)

\(x=4\)

_____

9. \(\left(15\times24-x\right):0,25=100:0,25\)

\(\left(15.24-x\right):0,25=400\)

\(15.24-x=400.0,25\)

\(15.24-x=100\)

\(360-x=100\)

\(x=360-100\)

\(x=260\)

1,x-8+32=68

=>x-8=68-32=36

=>x=36+8=42

2,x+8+32=68

=>x+8=68-32=36

=>x=36-8=28

3,98-x+34=43

=>98-x=43-34=9

=>x=98-9=89

4,98+x-34=43

=>98+x=43+34=77

=>x=77-98=-21

5,x:5:4=800

=>x:20=800

=>x=800x20=16000

6,18+x=384:8=48

=>x=48-18=30

7,(84,6-2x):3,02=5,1

=>84,6-2x=5,1x3,02=15,402

=>2x=84,6-15,402=69,198

=>x=69,198:2=34,599

8,5x=120:6=20

=>x=20:5=4

9,(15x24-x):0,25=100:0,25=400

=>360-x=400x0,25=100

=>x=360-100=260.

1. \(...\Rightarrow x+24=68\Rightarrow x=68-24=44\)

2. \(...\Rightarrow x+40=68\Rightarrow x=68-40=28\)

3. \(...\Rightarrow3^{2\left(8+x\right)}=9=3^2\Rightarrow2\left(8+x\right)=2\Rightarrow8+x=1\Rightarrow x=-7\)

4. \(...\Rightarrow3^{2\left(8+x\right)}=77\) (bạn xem lại đề)

5. \(...\Rightarrow x:5=800.4\Rightarrow x:5=3200\Rightarrow x=3200.5=16000\)

6. \(...\Rightarrow18+x=48\Rightarrow x=48-18=30\)

7. \(...\Rightarrow84,6-2x=5,1.3,02=15,402\Rightarrow2x=84,6-15,402\Rightarrow2x=69,198\Rightarrow x=34,599\)

8. \(...\Rightarrow5.x=20\Rightarrow x=20:5=4\)

9. \(\left(360-x\right):0,25=400\Rightarrow360-x=400.0,25=100\Rightarrow x=400-100=300\)

32 : 8 = 4

24 : 8 = 3

40 : 5 = 8

16 : 8 = 2

42 : 7 = 6

36 : 6 = 6

48 : 8 = 6

48 : 6 = 8

\(\dfrac{5}{6}-\dfrac{1}{3}=\dfrac{5}{6}-\dfrac{2}{6}=\dfrac{5-2}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)

\(\dfrac{2}{5}\times\dfrac{15}{8}=\dfrac{2\times15}{5\times8}=\dfrac{30}{40}=\dfrac{3}{4}\)

\(\dfrac{8}{5}+\dfrac{7}{6}+\dfrac{5}{9}-2=\dfrac{144}{90}+\dfrac{105}{90}+\dfrac{50}{90}-\dfrac{180}{90}=\dfrac{119}{90}\)

\(3-\dfrac{5}{6}-\dfrac{4}{9}+\dfrac{32}{24}=3-\dfrac{5}{6}-\dfrac{4}{9}+\dfrac{4}{3}=\dfrac{54}{18}-\dfrac{15}{18}-\dfrac{8}{18}+\dfrac{24}{18}=\dfrac{55}{18}\)

8/5+7/6+5/9-2=83/30+5/9-2

                       =299/90-2

                        =119/90

3-5/6-4/9+32/24=13/6-4/9+32/24

                          =13/18+32/24

                          =55/18

có sai đề bài ko vậy

1)-73

2)-5

3)-64

4)-56

5)9

6)-20

7)6

8)-2

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