tính từng các bước 11/143+-3/7 -8/7+-12/-30 5/10+-6/8 7/21+-30/-40 -19/5+2/3- 11/3+15/25 1/3+2/7+-8/21 VD ; 1/3+2/5 =1/3+2/5 =5/15+6/15 =11/15

Đáp án:

Giải thích các bước giải:

$\frac{11}{143}$ + $\frac{-3}{7}$ = $\frac{11}{143}$ – $\frac{3}{7}$ = $\frac{77}{1001}$ +$\frac{429}{1001}$ = $\frac{506}{1001}$ = $\frac{46}{91}$

$\frac{-8}{7}$ + $\frac{-12}{-30}$ = $\frac{-8}{7}$ + $\frac{2}{5}$ = $\frac{-40}{35}$ +$\frac{14}{35}$ = $\frac{-26}{35}$

$\frac{5}{10}$ + $\frac{-6}{8}$ = $\frac{1}{2}$ – $\frac{3}{4}$ = $\frac{2}{4}$ – $\frac{3}{4}$ = $\frac{-1}{4}$

$\frac{7}{21}$ + $\frac{-30}{-40}$ = $\frac{1}{3}$ + $\frac{3}{4}$ = $\frac{4}{12}$ + $\frac{9}{12}$ = $\frac{13}{12}$

$\frac{-19}{5}$ + $\frac{2}{3}$ – $\frac{11}{3}$ + $\frac{15}{25}$ = $\frac{-19}{5}$ + $\frac{2}{3}$ – $\frac{11}{3}$ + $\frac{3}{5}$ = $\frac{-57}{15}$ + $\frac{10}{15}$ – $\frac{55}{15}$ + $\frac{9}{5}$ = $\frac{-93}{15}$ = $\frac{-31}{5}$

$\frac{1}{3}$ + $\frac{2}{7}$ + $\frac{-8}{21}$ = $\frac{7}{21}$ + $\frac{6}{21}$ + $\frac{-8}{21}$ = $\frac{5}{21}$