1. a) -3 +2/5 b) -333/777 +22/55 2. A= 4/7 + 3/4 + 2/7 + 5/4 + 1/7 B= -3/4 + 2/7 + -1/4 + 3/5 + -5/7 C= -5/9 + 8/15 + -2/11 + 4/-9 + 7/15 D= -2/17 + 15/23 + -15/17 + 4/19 +8/23 ** Chú ý: dấu ( / ) nghĩ là phần Giúp mình với mình cần gấp sáng mai mình phải nộp rồi 😭

Giải thích các bước giải:

1.

a) -3 + $\frac{2}{5}$ = $\frac{-15}{5}$ + $\frac{2}{5}$ = $\frac{-15+2}{5}$ = $\frac{-13}{5}$

b) $\frac{-333}{777}$ + $\frac{22}{55}$ = $\frac{-3}{7}$ + $\frac{2}{5}$ = $\frac{-15}{35}$ + $\frac{14}{35}$ = $\frac{-15+14}{35}$ = $\frac{-1}{35}$ 

2.

A = $\frac{4}{7}$ + $\frac{3}{4}$ + $\frac{2}{7}$ + $\frac{5}{4}$ + $\frac{1}{7}$ = $\frac{4+2+1}{7}$ + $\frac{3+5}{4}$ = $\frac{7}{7}$ + $\frac{8}{4}$ = 1 + 2 = 3

B = $\frac{-3}{4}$ + $\frac{2}{7}$ + $\frac{-1}{4}$ + $\frac{3}{5}$ + $\frac{-5}{7}$ = $\frac{-3+(-1)}{4}$ + $\frac{2+(-5)}{7}$ + $\frac{3}{5}$ = $\frac{-4}{4}$ + $\frac{-3}{7}$ + $\frac{3}{5}$ = 1 + $\frac{-3}{7}$ + $\frac{3}{5}$ = $\frac{-35-15+21}{35}$ = $\frac{-29}{35}$ 

C = $\frac{-5}{9}$ + $\frac{8}{15}$ + $\frac{-2}{11}$ + $\frac{4}{-9}$ + $\frac{7}{15}$ = $\frac{-5}{9}$ + $\frac{8}{15}$ + $\frac{-2}{11}$ + $\frac{-4}{9}$ + $\frac{7}{15}$ = $\frac{-5-4}{9}$ + $\frac{8+7}{15}$ + $\frac{-2}{11}$ = $\frac{-9}{9}$ + $\frac{15}{15}$ + $\frac{-2}{11}$ = -1 + 1 + $\frac{-2}{11}$ = 0 + $\frac{-2}{11}$ = $\frac{-2}{11}$ 

D = $\frac{-2}{17}$ + $\frac{15}{23}$ + $\frac{-15}{17}$ + $\frac{4}{19}$ + $\frac{8}{23}$ = $\frac{-2-15}{17}$ + $\frac{15+8}{23}$ + $\frac{4}{19}$ = $\frac{-17}{17}$ + $\frac{23}{23}$ + $\frac{4}{19}$ = -1 + 1 + $\frac{4}{19}$ = 0 + $\frac{4}{19}$ = $\frac{4}{19}$