\(3+\frac{3}{5}+\frac{3}{25}+\frac{3}{125}+\frac{3}{625}\)

\(=3\left(1+\frac{1}{5}+\frac{1}{25}+\frac{1}{125}+\frac{1}{625}\right)\)

\(=3\cdot\frac{781}{625}\)

\(=\frac{2343}{625}\)

Cảm ơn bạn rất rất nhìu nhé.

Đặt A = \(3+\frac{3}{5}+\frac{3}{25}+\frac{3}{125}\)\(+\frac{3}{625}\)

=> 625 x A = 625 x 3 + 625 x\(\frac{3}{5}\)+ 625 x \(\frac{3}{25}\)+ 625 x \(\frac{3}{125}\)+ 625 x \(\frac{3}{625}\)

=> 625 x A = 1875 + 375 + 75 + 15 + 3

                  = 2343

=> A = \(\frac{2343}{625}\)

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120 dm² x 5 + 4m² = 600 dm² +  4 m² = 6 m² + 4m² = 10 m²

câu 3 đúng ko bạn?

em mới lớp 5

Cách 1 :

Ta có : \(1-\frac{4}{11}=\frac{7}{11};1-\frac{8}{15}=\frac{7}{15}\)

Vì \(\frac{7}{11}>\frac{7}{15}\)nên \(\frac{4}{11}< \frac{8}{15}\).

Cách 2 :

Vì \(\frac{4}{11}< \frac{4}{8}=\frac{1}{2};\frac{1}{2}=\frac{8}{16}< \frac{8}{15}\)nên \(\frac{4}{11}< \frac{8}{15}\).

~ HOK TỐT ~

Cách 1:

  \(1-\frac{4}{11}=\frac{7}{11}\)

\(1-\frac{8}{15}=\frac{7}{15}\)

Vì \(\frac{7}{11}>\frac{7}{15}\Rightarrow\frac{4}{11}< \frac{8}{15}\)

Cách 2:

     \(\frac{4}{11}=\frac{60}{165}\)

      \(\frac{8}{15}=\frac{88}{165}\)

Vì \(\frac{60}{165}< \frac{88}{165}\)

\(\Rightarrow\frac{4}{11}< \frac{8}{15}\)

Cách 3:

    Ta có:

 \(\frac{4}{11}=\frac{8}{22}< \frac{8}{15}\)

\(\Rightarrow\frac{4}{11}< \frac{8}{15}\)

      Cách 4:

\(\frac{4}{11}-1=\frac{-7}{11}\)

\(\frac{8}{15}-1=\frac{-7}{15}\)

Vì \(\frac{-7}{11}< \frac{-7}{15}\)\(\Rightarrow\frac{4}{11}< \frac{8}{15}\)

1B

2D

3C

4D

5A

1. C

2. D

3. C

4. D

5. A

đề:)?

a)(-45).312-312-54.312

=312.[(-45)-1-54]

=312.(-100)

=-31200

b)217.(-46)-217.15-217.40+27

=217.[(-46)-15-40]+27

=217.(-101)+27

=217.[(-100)+(-1)]+27

=-21700+(-217)+27

=-21700+(-190)

=-21890

-43.15+43.48-48.43+48.15

=(-43.15+48.15)-(43.48-48.43)

=5.15-0=75

ai tick tui tui tick lại