\(\frac{10}{25}=\frac{10:5}{25:5}=\frac{2}{5}\)

\(\frac{5}{20}=\frac{5:5}{20:5}=\frac{1}{4}\)

\(\frac{6}{30}=\frac{6:6}{30:6}=\frac{1}{5}\)

\(\frac{60}{20}=\frac{60:20}{20:20}=3\)

a ) \(\frac{2.9+6.7}{8.5+4.2}\)

= \(\frac{2.9+2.3.7}{2.2.2.5+4.2}\)

= \(\frac{9+3.7}{2.5+4.2}\)= \(\frac{30}{18}\)= \(\frac{5}{3}\)

a,  2.9+6.7/8.5+4.2

=2.3.3+2.3.7/2.4.5+2.4

=2.3.(3+7)/2.4.(5+1)

=30/24

=5/4

b,297-15/1188-60

=282/1128

=1/4

c, 2^5.3^7+2^5.3^2/2^6.3^10

=2^5.(3^7+3^2)/2.2^5.3^10

=3^9/2.3.3^9

=1/6

\(M=\frac{2.6.10+4.12.20+6.18.30+...+20.60.100}{1.2.3+2.4.6+3.6.9+...+10.20.30}\)

\(=\frac{2.6.10.\left(1+2+3+...+10\right)}{1.2.3.\left(1+2+3+...+10\right)}\)

\(=20\)

a, \(\frac{13.2-13.3}{1-27}\)=\(\frac{13.\left(2-3\right)}{-26}\)=\(\frac{13.\left(-1\right)}{-26}\)=\(\frac{-13}{-26}\)=\(\frac{1}{2}\)

b,\(\frac{15.\left(-3\right)+23.15}{-5+20}\)=\(\frac{15.[\left(-3\right)+23]}{15}\)=\(\frac{15.20}{15}\)=\(\frac{300}{15}\)=20

Chúc bạn học tốt

Tách ra 2 phần

Tử trước: Số các số hạng là:

 ( 24 - 3 ) : 3 + 1 = 8 (số)

Tổng là:

 ( 24 + 3 ) x 8 : 2 = 108

Mẫu: Số các số hạng là:

 ( 60 - 30 ) : 3 + 1 = 11 (số)

Tổng là: 

  ( 60 + 30 ) x 11 : 2 = 495

Vậy ta có phân số: \(\frac{108}{495}=\frac{12}{55}\)

Tính các tổng dưới đây sau khi đã rút gọn phân số :

a)\(\dfrac{7}{21}\) + \(\dfrac{9}{-36}\) = \(\dfrac{7}{21}\)+\(\dfrac{-9}{36}\)=\(\dfrac{1}{3}\)+\(\dfrac{-1}{4}\)=\(\dfrac{4}{12}\)+\(\dfrac{-3}{12}\)=\(\dfrac{1}{12}\)

b) \(\dfrac{-12}{18}\)+\(\dfrac{-21}{35}\)=\(\dfrac{-2}{3}\)+\(\dfrac{-3}{5}\)=\(\dfrac{-10}{15}\)+\(\dfrac{-9}{15}\)=\(\dfrac{-19}{15}\)

c) \(\dfrac{-3}{21}\)+\(\dfrac{6}{42}\)=\(\dfrac{-1}{7}\)+\(\dfrac{1}{7}\)=0

d) \(\dfrac{-18}{24}\)+\(\dfrac{15}{-21}\)=\(\dfrac{-18}{24}\)+\(\dfrac{-15}{21}\)=\(\dfrac{-3}{4}\)+\(\dfrac{-5}{7}\)=\(\dfrac{-21}{28}\)+\(\dfrac{-20}{28}\)=\(\dfrac{-41}{28}\)

a, 30/48=5/8

b,-104/182=-4/7

hoc tot

...

a>\(\frac{30}{48}=\frac{5}{8}\)

b>\(\frac{-104}{182}=\frac{-4}{7}\)

a)\(\dfrac{-3}{29}+\dfrac{16}{58}\)\(=\dfrac{-3}{29}+\dfrac{8}{29}=\dfrac{5}{29}\)

b) \(\dfrac{8}{40}+\dfrac{-36}{45}=\dfrac{1}{5}+\dfrac{-4}{5}=\dfrac{-3}{5}\)

c) \(\dfrac{-8}{18}+\dfrac{-15}{27}=\dfrac{-4}{9}+\dfrac{-5}{9}=\dfrac{-9}{9}=-1\)

a) \(\dfrac{-3}{29}+\dfrac{16}{58}=\dfrac{-3}{29}+\dfrac{8}{29}=\dfrac{-3+8}{29}=\dfrac{5}{29}\)

b) \(\dfrac{8}{40}+\dfrac{-36}{45}=\dfrac{1}{5}+\dfrac{-4}{5}=\dfrac{1+\left(-4\right)}{5}=\dfrac{-3}{5}\)

c) \(\dfrac{-8}{18}+\dfrac{-15}{27}=\dfrac{-4}{9}+\dfrac{-5}{9}=\dfrac{-4+\left(-5\right)}{9}=\dfrac{-9}{9}=-1\)

1/ ĐÁP ÁN:

\(\frac{-9}{33}=\frac{3}{-11}\); \(\frac{15}{9}=\frac{5}{3}\); \(\frac{-12}{19}=\frac{60}{-95}\)

2/ ĐÁP ÁN:

\(\frac{-7}{20}=\frac{3}{-18}=\frac{-9}{54}\ne\frac{12}{18}=\frac{-10}{-15}\ne\frac{14}{20}\)

3/ ĐÁP ÁN:

\(\frac{2}{3}=\frac{40}{60}\); \(\frac{3}{4}=\frac{45}{60}\); \(\frac{4}{5}=\frac{48}{60}\); \(\frac{5}{6}=\frac{50}{60}\)