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a) 9/22 và 33/18 = 1/2 x 3/2 = 3/4
b) 12/35 : 36/25 = 12/35 X 25/36 = 1/7 x 5/3 = 5/21
c) 19/17 : 76/51 = 19/17 x 51/76 = 1/1 x 3/4 = 3/4
k mk nha
\(25\frac{2}{13}-\left(\frac{15}{17}+15\frac{2}{3}\right)=\frac{327}{13}-\left(\frac{15}{17}+\frac{47}{3}\right)\)
\(=\frac{327}{13}-\frac{844}{51}\)
\(=\frac{5705}{663}\)
\(\frac{5}{30}+\frac{15}{90}+\frac{250}{150}+\frac{350}{210}+\frac{45}{270}=\frac{1}{6}+\frac{1}{6}+\frac{5}{3}+\frac{5}{3}+\frac{1}{6}\)
\(=\frac{3}{6}+\frac{10}{3}\)
\(=\frac{1}{2}+\frac{10}{3}\)
\(=\frac{23}{6}\)
\(3\frac{1}{11}.\frac{27}{46}.1\frac{6}{17}.2\frac{4}{9}=\frac{34}{11}.\frac{27}{46}.\frac{23}{17}.\frac{22}{9}\)
\(=\frac{68}{9}.\frac{27}{34}\)
\(=6\)
Bài 1:
\(A=\frac{5}{3.6}+\frac{5}{6.9}+....+\frac{5}{96.99}\)
\(\Rightarrow\frac{3}{5}A=\frac{3}{3.6}+\frac{3}{6.9}+....+\frac{3}{96.99}\)
\(\Rightarrow\frac{3}{5}A=\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{9}+...+\frac{1}{96}-\frac{1}{99}\)
\(=\frac{1}{3}-\frac{1}{99}=\frac{32}{99}\)
\(\Rightarrow A=\frac{32}{99}\div\frac{3}{5}=\frac{160}{297}\)
Bái 2:
\(B=\frac{2}{3.7}+\frac{2}{7.11}+...+\frac{2}{99.103}\)
\(\Rightarrow2B=\frac{4}{3.7}+\frac{4}{7.11}+....+\frac{4}{99.103}\)
\(\Rightarrow2B=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+....+\frac{1}{99}-\frac{1}{103}\)
\(=\frac{1}{3}-\frac{1}{103}=\frac{100}{309}\)
\(\Rightarrow B=\frac{100}{309}\div2=\frac{50}{309}\)
Bài 1:
Ta có:
\(\frac{5}{n.\left(n+3\right)}=\frac{5}{3}.\frac{3}{n.\left(n+3\right)}=\frac{5}{3}.\frac{\left(n+3\right)-n}{n.\left(n+3\right)}=\frac{5}{3}.\left[\frac{n+3}{n.\left(n+3\right)}-\frac{n}{n\left(n+3\right)}\right]\)\(=\frac{5}{3}\left(\frac{1}{n}-\frac{1}{n+3}\right)\)
\(\frac{5}{3.6}+\frac{5}{6.9}+\frac{5}{9.12}+...+\frac{5}{96.99}=\frac{5}{3}\left(\frac{1}{3}-\frac{1}{6}+\frac{1}{6}-\frac{1}{9}+...+\frac{1}{96}-\frac{1}{99}\right)\)
6 2/7 + 7 3/5 + 8 6/9 + 9 1/4 + 2/5 + 5/7 + 1/3 x 3/4 + 1967
= 44/7 + 38/5 + 78/9 + 37/4 + 2/5 + 5/7 + 1/3 + 1967
= ( 44/7 + 5/7 ) + ( 38/5 + 2/5 ) + ( 26/3 + 1/3 ) + ( 37/4 + 3/4 ) +1967
= 7 + 8 + 9 + 10 + 1967
= 15 + 9 + 10 + 1967
= 24 + 10 + 1967
= 34 + 1967
= 2001
a , Theo thứ tự từ bé đến lớn : 1/12 , 2/3 , 3/4 , 5/6
b, Tính
a, 3/ 4 + 2/3 + 5/12 = 9/12 + 8/12 + 5/12 = 11/6
b, 7/8 - 7/16 - 11/32 = 28/32 - 14/32 - 11/32 = 3/32
c, 3/5 x 2/7 x 5/6 = 3 x 2 x 5 / 5 x 7 x 6 = 3 x 2 x 5 / 5 x 7 x 3 x 2 = 1/7
d , 15/16 : 3/8 x 3/4 = 15/16 x 8/3 x 3/4 = 15 x 8 x 3 / 16 x 3 x4 = 3 x 5 x 8 x 3 / 8 x 2 x 3 x 4 = 15/8
a) 1/12; 2/3; 3/4; 5/6
b)
a) 3/4 + 2/3 + 5/12 = 9/12 + 8/12 + 5/12 = 17/12 + 5/12 = 22/12 = 11/6
b) 7/8 - 7/16 - 11/32 = 28/32 - 14/32 - 11/32 = 14/32 - 11/32 = 3/32
c) 3/5 x 2/7 x 5/6 = 6/35 x 5/6 = 30/210 = 1/70
d) 15/16 : 3/8 x 3/4 = 15/16 x 8/3 x3/4 = 120/48 x 3/4 = 360/192 = 8/15
