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a) \(\dfrac{17}{8}-2=\dfrac{1}{8}\)
b) \(\dfrac{189}{45}-3=\dfrac{6}{5}\)
c) \(3-\dfrac{5}{7}=\dfrac{16}{7}\)
d) \(5-\dfrac{1515}{1818}=\dfrac{25}{6}\)
Bài 1:
Rút gọn các phân số sau:
\(\dfrac{12}{24}\) = \(\dfrac{12:12}{24:12}\) = \(\dfrac{1}{2}\)
\(\dfrac{120}{90}\) = \(\dfrac{120:30}{90:30}\) = \(\dfrac{4}{3}\)
\(\dfrac{42}{24}\) = \(\dfrac{42:6}{24:6}\) = \(\dfrac{7}{4}\)
Bài 2:
Tính bằng cách thuận tiện:
\(\dfrac{13}{19}\) + \(\dfrac{18}{19}\) + \(\dfrac{17}{19}\)
= \(\dfrac{13+18+17}{19}\)
= \(\dfrac{\left(13+17\right)+18}{19}\)
= \(\dfrac{48}{19}\)
\(\dfrac{12}{17}\) + \(\dfrac{19}{17}\) + \(\dfrac{8}{17}\)
= \(\dfrac{12+19+8}{17}\)
= \(\dfrac{\left(12+8\right)+19}{17}\)
= \(\dfrac{39}{17}\)
a) 189 : 3 x 8 > 189 : 9 x 8
b) 25 x 17 > 27 x 15
k mk nha
a) \(\frac{2}{9}+\frac{5}{6}\times\frac{4}{7}\)
\(=\frac{2}{9}+\frac{10}{21}\)
\(=\frac{44}{63}\)
b) \(\frac{21}{25}+\frac{4}{5}:\frac{8}{6}\)
\(=\frac{21}{25}+\frac{3}{5}\)
\(=\frac{36}{25}\)
c) \(\frac{17}{24}-\frac{1}{3}+\frac{3}{4}\)
\(=\frac{3}{8}+\frac{3}{4}\)
\(=\frac{9}{8}\)
a) \(\frac{2}{9}+\frac{5}{6}\times\frac{4}{7}=\frac{2}{9}+\frac{10}{21}=\frac{14}{63}+\frac{30}{63}=\frac{44}{63}\)
b) \(\frac{21}{25}+\frac{4}{5}\div\frac{8}{6}=\frac{21}{25}+\frac{4}{5}\times\frac{6}{8}=\frac{21}{25}+\frac{3}{5}=\frac{21}{25}+\frac{15}{25}=\frac{36}{25}\)
c) \(\frac{17}{24}-\frac{1}{3}+\frac{3}{4}=\frac{17}{24}-\frac{8}{24}+\frac{18}{24}=\frac{27}{24}=\frac{9}{8}\)
Bài 1: Tính
\(a.\frac{15}{16}-\frac{7}{16}=\frac{15-7}{16}=\frac{8}{16}=\frac{1}{2}\)
\(b.\frac{7}{4}-\frac{3}{4}=\frac{7-3}{4}=\frac{4}{4}=1\)
\(c.\frac{9}{5}-\frac{3}{5}=\frac{9-3}{5}=\frac{6}{5}\)
\(d.\frac{17}{49}-\frac{12}{49}=\frac{17-12}{49}=\frac{5}{49}\)
Bài 2:Rút gọn rồi tính
\(a.\frac{2}{3}-\frac{3}{9}=\frac{2}{3}-\frac{1}{3}=\frac{2-1}{3}=\frac{1}{3}\)
\(b.\frac{7}{5}-\frac{15}{25}=\frac{7}{5}-\frac{3}{5}=\frac{7-3}{5}=\frac{4}{5}\)
Học tốt. K cho mik nha
2 - 5/6 = 2/1 - 5/6 = 12/6 - 5/6 = 12-5/ 6= 7/6
7/8 + 3/4 = 7/8 + 6 / 8 = 7+8/8 = 15/8
2/5 + 3/4 = 8/20 + 15/20 = 8+15/20 = 23/20
2 - 5/6 = 2/1 - 5/6 = 12/6 - 5/6 = 12-5/6 = 7/6
7/8 + 3/4 = 7/8 + 6/8 = 7 + 8/8 =15/8
2/5 + 3/4 = 8/20 + 15/20 = 8 + 15/20 = 23/20
a) 3/7+5/2+4/7
=(3/7+4/7)+5/2
=1+5/2
=7/2
b)6/8+4/5+1/4
=(6/8+1/4)+4/5
=1+4/5
=9/5
đến đó thôi mệt quá
a = 1/8
b = 16/7
c = 186
=:1/8 ;7/16 ;186