a) \(\dfrac{-7}{20}=\dfrac{-3}{20}+\dfrac{-4}{20}=\dfrac{-3}{20}+\dfrac{-1}{5}\)

b) Phải là hiệu của 2 số hữu tỉ dương chứ nhỉ ?

\(\dfrac{-7}{20}=\dfrac{8}{20}-\dfrac{15}{20}=\dfrac{2}{5}-\dfrac{3}{4}\)

1/ Cách 1: Ta có: \(\dfrac{-8}{15}\) = \(\dfrac{-1+\left(-7\right)}{15}\) = \(\dfrac{-1}{15}\) + \(\dfrac{-7}{15}\)

Cách 2: Ta có: \(\dfrac{-8}{15}\) = \(\dfrac{-2+\left(-6\right)}{15}\) = \(\dfrac{-2}{15}\) + \(\dfrac{-6}{15}\) = \(\dfrac{-2}{15}\) + \(\dfrac{-2}{5}\)

Cách 3: Ta có: \(\dfrac{-8}{15}\) = \(\dfrac{-3+\left(-5\right)}{15}\) = \(\dfrac{-3}{15}\) + \(\dfrac{-5}{15}\) = \(\dfrac{-1}{5}\) + \(\dfrac{-1}{3}\)

2/ C1: Ta có: \(\dfrac{-8}{15}=\dfrac{10-18}{15}=\dfrac{10}{15}-\dfrac{18}{15}=\dfrac{2}{3}-\dfrac{6}{5}\)

C2: Ta có: \(\dfrac{-8}{15}=\dfrac{1-9}{15}=\dfrac{1}{15}-\dfrac{9}{15}=\dfrac{1}{15}-\dfrac{3}{5}\)

C3: Ta có: \(\dfrac{-8}{15}=\dfrac{5-13}{15}=\dfrac{5}{15}-\dfrac{13}{15}=\dfrac{1}{3}-\dfrac{13}{15}\)

3/C1: Ta có: \(\dfrac{-8}{15}=\dfrac{-16+8}{15}=\dfrac{-16}{15}+\dfrac{8}{15}\)

C2: Ta có: \(\dfrac{-8}{15}=\dfrac{-20+12}{15}=\dfrac{-20}{15}+\dfrac{12}{15}=\dfrac{-4}{3}+\dfrac{4}{5}\)

C3: Ta có:\(\dfrac{-8}{15}=\dfrac{-14+6}{15}=\dfrac{-14}{15}+\dfrac{6}{15}=\dfrac{-14}{15}+\dfrac{2}{5}\)

Mk chỉ nghĩ z thôi chứ ko biết đúng hay sai nữa, có j thì góp ý nha. Chúc bn hc tốt!!!

a) \(-\frac{15}{32}=-\frac{1}{4}+\left(-\frac{7}{32}\right)\)

b) \(-\frac{15}{32}=\frac{1}{32}-\frac{1}{2}\)

a) \(\dfrac{-15}{37}=\dfrac{-12}{37}+\dfrac{-3}{37}\)

b) \(\dfrac{-15}{37}=\dfrac{29}{37}-\dfrac{44}{37}\)

a) -3/20 + -4/20 = -7/20

b) 1/20 - 8/20 = -7/20 

học tốt, nhớ cố gắng

ơ sao sai

MÌNH KO ẤN SAI NHÉ

a, - \(\dfrac{11}{25}\) = \(\dfrac{-6}{25}\) + \(\dfrac{-5}{25}\) + 

    - \(\dfrac{11}{25}\) =  \(\dfrac{-1}{25}\) + \(\dfrac{-10}{25}\) + 

    - \(\dfrac{11}{25}\) = \(\dfrac{-3}{25}\) + \(\dfrac{-8}{25}\) +  

b, - \(\dfrac{11}{25}\) = \(\dfrac{6}{25}\) - \(\dfrac{17}{25}\)

   - \(\dfrac{11}{25}\) = \(\dfrac{7}{25}\) - \(\dfrac{18}{25}\)

  - \(\dfrac{11}{25}\)  = \(\dfrac{8}{25}\) - \(\dfrac{19}{25}\)

Câu 1.

$\frac{1}{15}-\frac{9}{15}=\frac{-8}{15}$

$\frac{2}{15}-\frac{10}{15}=\frac{-8}{15}$

$\frac{3}{15}-\frac{11}{15}=\frac{-8}{15}$

Câu 2:

$\frac{-9}{15}+\frac{1}{15}=\frac{-8}{15}$

$\frac{-10}{15}+\frac{2}{15}=\frac{-8}{15}$

$\frac{-11}{15}+\frac{3}{15}=\frac{-8}{15}$

Câu 3:

$\frac{-7}{15}-\frac{1}{15}=\frac{-8}{15}$

$\frac{-6}{15}-\frac{2}{15}=\frac{-8}{15}$

$\frac{-5}{15}-\frac{3}{15}=\frac{-8}{15}$