a) \(A=\frac{27\text{x}45+27\text{x}25}{2+4+6+8+...+18}=\frac{27\left(45+25\right)}{\left(18+2\right)\text{x}\left(\frac{18-2}{2}+1\right)}\)

\(A=\frac{27\text{x}70}{20\text{x}9}=\frac{3\text{x}9\text{x}10\text{x}7}{10\text{x}2\text{x}9}\)

\(A=\frac{21}{2}\)

b) \(B=\frac{28\text{x}108-52\text{x}12}{32-28+24-20+16-12+8-4}\)

\(B=\frac{28\text{x}12\text{x}9\text{​​}\text{​​}-52\text{x}12}{\left(32-28\right)+\left(24-20\right)+\left(16-12\right)+\left(8-4\right)}\)

\(B=\frac{12\left(28\text{x}9-52\right)}{4+4+4+4}=\frac{12\text{x}200}{4\text{x}4}\)

\(B=\frac{4\text{x}3\text{x}4\text{x}50}{4\text{x}4}=150\)

cám ơn bn

\(\frac{8}{5}-\frac{18}{27}\)

\(=\frac{8}{5}-\frac{2}{3}\)

\(=\frac{24}{15}-\frac{10}{15}\)

\(=\frac{14}{15}\)

\(\frac{12}{20}-\frac{6}{18}\)

\(=\frac{3}{5}-\frac{1}{3}\)

\(=\frac{9}{15}-\frac{5}{15}\)

\(=\frac{4}{15}\)

\(\frac{8}{24}-\frac{5}{25}\)

\(=\frac{1}{3}-\frac{1}{5}\)

\(=\frac{5}{15}-\frac{3}{15}\)

\(=\frac{2}{15}\)

\(\frac{18}{21}-\frac{12}{27}\)

\(=\frac{6}{7}-\frac{4}{9}\)

\(=\frac{54}{63}-\frac{28}{63}\)

\(=\frac{26}{63}\)

1)8/5-2/3=14/15

2)3/5-1/3=4/15

3)1/3-1/5=2/15

4)6/7-4/9=26/63

a.

\(\frac{34}{48}=\frac{17}{24}=\frac{51}{72}\)                 \(\frac{1313}{1818}=\frac{13}{18}=\frac{52}{72}\)

Có : \(\frac{51}{72}< \frac{52}{72}\Rightarrow\frac{34}{48}< \frac{1313}{1818}\)

b.

\(\)

a,\(\frac{16}{27}\)> \(\frac{15}{29}\)

b,\(\frac{26}{50}\)> \(\frac{14}{29}\)

c,\(\frac{327}{326}\)< \(\frac{326}{325}\)

Tk nha!!

\(a,\frac{16}{27}>\frac{15}{29}\)

\(b,\frac{26}{50}>\frac{14}{29}\)

\(c,\frac{327}{326}< \frac{326}{325}\)

~ Chúc bạn học tốt ~

c 12/27

C nhen

TL

4/16+1/4=1/4+14=2/4=1/2

b) 15/25+6/10=3/5+3/5=6/5

c)5/9+21/27=5/9+7/9=4/3

HT

\(a)\) \(\dfrac{4}{16} + \dfrac{1}{4} = \dfrac{1}{4}+ \dfrac{1}{4} = \dfrac{2}{4} = \dfrac{1}{2} \)

\(b) \dfrac{15}{25} + + \dfrac{6}{10} = \dfrac{3}{5} + \dfrac{3}{5} =\dfrac{6}{5} \)

\(c) \dfrac{5}{9} + \dfrac{21}{27} = \dfrac{5}{9} + \dfrac{7}{9} = \dfrac{12}{9} = \dfrac{4}{3}\)

a) \(\frac{13}{19}+\frac{18}{19}+\frac{19}{19}=\left(\frac{13}{19}+\frac{17}{19}\right)+\frac{18}{19}=\frac{20}{19}+\frac{18}{19}=\frac{48}{19}\)

b) \(\frac{3}{5}+\frac{3}{16}+\frac{13}{16}=\left(\frac{3}{16}+\frac{13}{16}\right)+\frac{3}{5}=1+\frac{3}{5}=\frac{5}{5}+\frac{3}{5}=\frac{8}{5}\)

a) \(\frac{13}{19}+\frac{18}{19}+\frac{17}{19}\)

= \(\frac{31}{19}+\frac{17}{19}\)

= \(\frac{48}{19}.\)

b) \(\frac{3}{5}+\frac{3}{16}+\frac{13}{16}\)

= \(\frac{3}{5}+\left(\frac{3}{16}+\frac{13}{16}\right)\)

= \(\frac{3}{5}+\frac{16}{16}\)

= \(\frac{3}{5}+1\)

= \(\frac{3}{5}.\)