bn ra từng câu 1 thui đừng ra nhìu làm chán lém

10-9/16=91/10

5+3/5=28/5

3/8

9/10

10/3

1/6

50/3

B2

3/4

5/21

51/28

\(\frac{8}{9}+\frac{1}{3}=\frac{8}{9}+\frac{3}{9}=\frac{11}{9}\)

\(\frac{8}{9}+\frac{1}{3}=\frac{8}{9}+\frac{3}{9}=\frac{11}{9}\)

\(\frac{24}{15}-\frac{20}{25}=\frac{24}{15}-\frac{4}{5}=\frac{24}{15}-\frac{12}{15}=\frac{12}{15}\)

\(3\frac{1}{6}\times2\frac{3}{5}=\frac{19}{6}\times\frac{13}{5}=\frac{247}{30}\)

\(2\frac{1}{10}\div2\frac{2}{5}=\frac{21}{10}\div\frac{12}{5}=\frac{21}{10}\times\frac{5}{12}=\frac{7}{8}\)

Dùng máy tính đấy em ơi

a, Sai

b, Đúng

c, đúng 

d, Sai

a,\(2\frac{2}{5}+1\frac{2}{5}=3\frac{2}{5}\left(S\right)\)

b,\(6\frac{3}{4}-1\frac{1}{4}=5\frac{2}{4}\left(\text{Đ}\right)\)

c,\(3\frac{1}{2}\times2\frac{2}{3}=9\frac{1}{3}\left(\text{Đ}\right)\)

d,\(4\frac{1}{6}\div2\frac{1}{5}=2\frac{5}{6}\left(S\right)\)

bài 6 \(\frac{2}{2\times4}+\frac{2}{4\times6}+\frac{2}{6\times8}+\ldots+\frac{2}{80\times82}+\frac{2}{82\times84}\)

= \(\frac12-\frac14+\frac14-\frac16+\frac16-\cdots+\frac{1}{80}-\frac{1}{82}+\frac{1}{82}-\frac{1}{84}\)

= \(\frac12-\left(\frac14-\frac14\right)-\left(\frac16-\frac16\right)-\cdots-\left(\frac{1}{82}-\frac{1}{82}\right)-\frac{1}{84}\)

=\(\frac12-0-0-\frac{1}{84}\)

=\(\frac12\) - \(\frac{1}{84}\)

=\(\frac{42}{84}-\frac{1}{84}\)

=\(\frac{41}{84}\)

Bài 7

a)\(\frac{19}{4}=4\frac34\)

b)\(\frac{27}{5}=5\frac25\)

c)\(\frac{56}{8}=7\frac08\)

biết làm nhưng tui lười ko muốn viết dài

a, 2\(\dfrac{3}{5}\) \(\times\) 1\(\dfrac{1}{4}\) + \(\dfrac{5}{2}\)

= \(\dfrac{13}{5}\) \(\times\) \(\dfrac{5}{4}\) + \(\dfrac{5}{2}\)

= \(\dfrac{13}{4}\) + \(\dfrac{5}{2}\)

= \(\dfrac{13}{4}\) + \(\dfrac{10}{4}\)

= \(\dfrac{23}{4}\)

(7x6=5+2+6x7) =

a) \(\frac{2}{5}+\left(\frac{2}{8}+\frac{3}{5}+\frac{6}{8}\right)=\left(\frac{2}{5}+\frac{3}{5}\right)+\left(\frac{2}{8}+\frac{6}{8}\right)=1+1=2\)

b) \(\frac{6}{9}+\left(\frac{15}{25}+\frac{12}{9}+\frac{6}{15}\right)=\left(\frac{6}{9}+\frac{12}{9}\right)+\left(\frac{15}{25}+\frac{6}{15}\right)\)

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