Hướng dẫn giải:

a) (32 + 128) : 4 = 32 : 4 + 128 : 4 = 8 + 32 = 40 

b) 240 : (2 + 5) = 240 : 2 + 240 : 5 = 120 + 48 = 168 

\(\dfrac{\sqrt{5}\left(\sqrt{5}-2\right)}{\sqrt{5}-2}-\dfrac{11\left(4-\sqrt{5}\right)}{16-5}=\sqrt{5}-4+\sqrt{5}=2\sqrt{5}-4\)

\(=\sqrt{5}-4+\sqrt{5}=2\sqrt{5}-4\)

                                                                Bài giải

a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)

\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)

b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)

\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)

c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)

d,  \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)

\(=1+1+1\)

\(=3\)

e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)

\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)

\(=1+1+1\)

\(=3\)

a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)

\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)

b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)

\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)

c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)

d,  \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)

\(=1+1+1\)

\(=3\)

e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)

\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)

\(=1+1+1\)

\(=3\)

) 2 x 6 = 12              3 x 7 = 21

12 : 2 = 6              21 : 3 = 7

12 : 6 = 2              21 : 7 = 3

4 x 8 = 32              5 x 9 = 45

32 : 4 = 8              45 : 5 = 9

32 : 8 = 4              45 : 9 = 5

b) 600 : 3 = 200        800 : 4 = 200        400 : 2 = 200

600 : 2 = 300        800 : 2 = 400        500 : 5 = 100

a) 2x6=12             3x7=21

12:2=6              21:3=7

12:6=2              21:7=3

4x8=32             5x9=45

32:4=8              45:5=9

32:8=4              45:9=5

b) 600:3=200       800:4=200       400:2=200

    600:2=300        800:2=400       500:5=100

A Legend Never Dies

Phương pháp giải:

- Nhẩm lại bảng nhân và chia trong phạm vi đã học rồi điền kết quả vào chỗ trống.

- Biểu thức có phép tính nhân và chia thì thực hiện phép tính từ trái sang phải.

Lời giải chi tiết:

x

cách giải bài này như nào: 5/20+1/4+6/24+8/32=bao nhiêu

    \(\dfrac{4}{5}\) : (\(\dfrac{4}{5}\) .- \(\dfrac{5}{4}\)) : (\(\dfrac{16}{25}\) - \(\dfrac{1}{5}\))

=  \(\dfrac{4}{5}\) : (-1) : (\(\dfrac{16}{25}\) - \(\dfrac{5}{25}\))

= -\(\dfrac{4}{5}\)  : \(\dfrac{11}{25}\)

= - \(\dfrac{4}{5}\) x \(\dfrac{25}{11}\)

=  - \(\dfrac{20}{11}\)

\(\dfrac{4}{5}\): (\(\dfrac{4}{5}\).-\(\dfrac{5}{4}\)) : (\(\dfrac{16}{25}\) - \(\dfrac{1}{5}\))

=\(\dfrac{4}{5}\) x - 1: (\(\dfrac{16}{25}\) - \(\dfrac{5}{25}\))

= - \(\dfrac{4}{5}\) : \(\dfrac{11}{25}\)

= - \(\dfrac{4}{5}\) x \(\dfrac{25}{11}\)

= - \(\dfrac{20}{11}\) 

\(\dfrac{11}{12}\): (\(\dfrac{7}{9}\) + - \(\dfrac{1}{3}\)) - (\(\dfrac{2}{3}\) - \(\dfrac{5}{15}\))

= \(\dfrac{11}{12}\) : (\(\dfrac{7}{9}\) - \(\dfrac{3}{9}\)) - (\(\dfrac{2}{3}\) - \(\dfrac{1}{3}\))

= \(\dfrac{11}{12}\) : \(\dfrac{4}{9}\) - \(\dfrac{1}{3}\)

= \(\dfrac{11}{12}\) x \(\dfrac{9}{4}\) - \(\dfrac{1}{3}\)

= \(\dfrac{99}{48}\) - \(\dfrac{16}{48}\)

= \(\dfrac{83}{48}\) 

\(32-2\left\{3^3-4\left[5^6:5^4-\left(3.7-1\right)\right]\right\}\)

\(=32-2\left[27-4\left(25-20\right)\right]\)

\(=32-2\left(27-100+80\right)\)

\(=32-2.7=32-14=18\)