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\(a,\dfrac{5}{4}+\dfrac{7}{3}=\dfrac{15}{12}+\dfrac{28}{12}=\dfrac{43}{12}\\ b,\dfrac{4}{5}\times\dfrac{5}{8}=\dfrac{4}{8}=\dfrac{1}{2}\\ c,\dfrac{2}{3}-\dfrac{3}{8}=\dfrac{16}{24}-\dfrac{9}{24}=\dfrac{7}{24}\\ d,\dfrac{5}{6}:\dfrac{1}{3}=\dfrac{5}{6}\times\dfrac{1}{3}=\dfrac{5}{18}\)
a) \(\dfrac{5}{4}+\dfrac{7}{3}=\dfrac{15}{12}+\dfrac{28}{12}=\dfrac{43}{12}\)
b) \(\dfrac{4}{5}\cdot\dfrac{5}{8}=\dfrac{20}{40}=\dfrac{1}{2}\)
c) \(\dfrac{2}{3}-\dfrac{3}{8}=\dfrac{16}{24}-\dfrac{9}{24}=\dfrac{7}{24}\)
d) \(\dfrac{5}{6}:\dfrac{1}{3}=\dfrac{5}{6}\cdot\dfrac{3}{1}=\dfrac{15}{6}\)
\(\frac{3}{9}\cdot\frac{5}{4}=\frac{1}{3}\cdot\frac{5}{4}\)
\(=\frac{1.5}{3.4}\)
\(=\frac{5}{12}\)
3/9=1/3
5/4=5/4(ko rút gọn đc)
3/9x5/4=5/12
NHỚ K CHO MK NHA
\(\frac{4.5.6.3}{8.6.5}=\frac{4.5.6.3}{2.4.6.5}=\frac{3}{2}\)
Bài 1:
a: \(=\dfrac{4}{8}+\dfrac{2}{8}+\dfrac{1}{8}=\dfrac{7}{8}\)
b: \(=\dfrac{4}{12}+\dfrac{2}{12}+\dfrac{1}{12}=\dfrac{7}{12}\)
B1:
a \(\dfrac{7}{8}\)
b \(\dfrac{7}{12}\)
B2:
a \(\dfrac{3}{7}\)
b \(\dfrac{5}{9}\)
c \(\dfrac{6}{5}\)
B3:
đội còn phải sửa phần quãng đường nữa :\(\dfrac{8}{15}\) phần quãng đường
1, Rút gọn rồi tính
a) \(\frac{4}{5}+\frac{3}{15}\)
= \(\frac{4}{5}+\frac{1}{5}\)
= \(\frac{5}{5}\)
= \(1\)
b) \(\frac{2}{3}+\frac{32}{24}\)
= \(\frac{2}{3}+\frac{4}{3}\)
= \(\frac{6}{3}\)
= \(2\)
c) \(\frac{5}{6}+\frac{15}{18}\)
= \(\frac{5}{6}+\frac{5}{6}\)
= \(\frac{10}{6}\)
= \(\frac{5}{3}\)
2, Tính rồi rút gọn
a) \(\frac{8}{15}+\frac{2}{3}\)
= \(\frac{8}{15}+\frac{10}{15}\)
= \(\frac{18}{15}\)
= \(\frac{6}{5}\)
b) \(\frac{3}{7}+\frac{4}{8}\)
= \(\frac{24}{56}+\frac{28}{56}\)
= \(\frac{52}{56}\)
= \(\frac{13}{14}\)
\(a)\frac{3}{4}+\frac{1}{3}+\frac{2}{5}=\frac{45+20+24}{60}=\frac{89}{60}\)
\(b)\)Rút gọn rồi tính
\(a)\frac{3}{18}+\frac{4}{7}=\frac{1}{6}+\frac{4}{7}=\frac{7+24}{42}=\frac{31}{42}\)
\(b)\frac{12}{24}+\frac{12}{15}=\frac{1}{2}+\frac{4}{5}=\frac{5+8}{10}=\frac{13}{10}\)
\(2/15 x 3/4 x 4/1 x 5/3 = 2 x 3 x 4 x 5/ 15 x 4 x 1x 3=120/180 = 2/3\)
\(\dfrac{2}{15}\times\dfrac{3}{4}\times\dfrac{4}{1}\times\dfrac{5}{3}=\dfrac{2}{15}\times\dfrac{3}{4}\times4\times\dfrac{5}{3}=\dfrac{2\times3\times4\times5}{15\times4\times3}=\dfrac{120}{180}=\dfrac{2}{3}\)