a) 2/3 + 1/2 + 1/6 b) 5/12 + 5/6 - 3/4 c) 1/3 x 3/5 x 2/5 d) 15/16 : 3/8 x 3/4
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Bài 1:
a: \(x=\dfrac{2}{3}:\dfrac{3}{5}=\dfrac{2}{3}\cdot\dfrac{5}{3}=\dfrac{10}{9}\)
b: \(x=\dfrac{17}{8}:\dfrac{7}{17}=\dfrac{17}{8}\cdot\dfrac{17}{7}=\dfrac{289}{56}\)
c: \(x=-\dfrac{3}{4}:\dfrac{7}{12}=\dfrac{-3}{4}\cdot\dfrac{12}{7}=\dfrac{-63}{28}=-\dfrac{9}{4}\)
d: \(\Leftrightarrow x\cdot\dfrac{1}{6}=\dfrac{3}{8}-\dfrac{1}{4}=\dfrac{1}{4}\)
hay \(x=\dfrac{1}{4}:\dfrac{1}{6}=\dfrac{3}{2}\)
e: \(\Leftrightarrow\dfrac{1}{2}:x=-4-\dfrac{1}{3}=-\dfrac{17}{3}\)
hay \(x=-\dfrac{1}{2}:\dfrac{17}{3}=\dfrac{-3}{34}\)
a, (\(\dfrac{9}{10}\) - \(\dfrac{15}{16}\)) \(\times\) ( \(\dfrac{5}{12}\) - \(\dfrac{11}{15}\) - \(\dfrac{7}{20}\))
= (\(\dfrac{72}{80}\) - \(\dfrac{75}{80}\)) \(\times\) (\(\)\(\dfrac{25}{60}\) - \(\dfrac{44}{60}\) - \(\dfrac{21}{60}\))
= - \(\dfrac{3}{80}\) \(\times\) (- \(\dfrac{2}{3}\))
= \(\dfrac{1}{40}\)
b, (-1)3 + (- \(\dfrac{2}{3}\))2 : 2\(\dfrac{2}{3}\) + \(\dfrac{5}{6}\)
= -13 + \(\dfrac{4}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{5}{6}\)
= -1 + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{3}{8}\) + \(\dfrac{5}{6}\)
= -1 + \(\dfrac{1}{6}\) + \(\dfrac{5}{6}\)
= -1 + 1
= 0
a, \(\frac{-5}{12}+\frac{4}{37}+\frac{17}{12}-\frac{41}{37}\)
\(=\left(-\frac{5}{12}+\frac{17}{12}\right)+\left[\frac{4}{37}+\left(-\frac{41}{37}\right)\right]\)
\(=1+\left(-1\right)\)
\(=-1\)
b, \(\frac{1}{2}+\left(-\frac{3}{5}\right):\left(-1\frac{1}{2}\right)-\left|-\frac{2}{5}\right|\)
\(=\frac{1}{2}+\left(-\frac{3}{5}\right):\left(-\frac{3}{2}\right)-\frac{2}{5}\)
\(=\frac{1}{2}+\frac{2}{5}-\frac{2}{5}\)
\(=\frac{1}{2}\)
Mấy bài còn lại tương tự bn tự làm nha tính số mũ ra xong thực hiện, lấy thừa số chung mà nhân ( H mik bận đi hc thêm rồi)
a) \(5+\dfrac{2}{3}=\dfrac{15}{3}+\dfrac{2}{3}=\dfrac{17}{3}\)
b) \(\dfrac{12}{5}\cdot\dfrac{1}{4}=\dfrac{3}{5}\)
c) \(\dfrac{3}{8}-\dfrac{1}{3}=\dfrac{9}{24}-\dfrac{8}{24}=\dfrac{1}{24}\)
d) \(\dfrac{6}{15}-\dfrac{1}{3}:\dfrac{5}{3}=\dfrac{6}{15}-\dfrac{1}{3}\cdot\dfrac{3}{5}=\dfrac{6}{15}-\dfrac{1}{5}=\dfrac{6}{15}-\dfrac{3}{15}=\dfrac{3}{15}=\dfrac{1}{5}\)
\(5+\dfrac{2}{3}=\dfrac{5}{1}+\dfrac{2}{3}=\dfrac{15}{3}+\dfrac{2}{3}=\dfrac{17}{9};\dfrac{12}{5}x\dfrac{1}{4}=\dfrac{12}{40};\dfrac{3}{8}-\dfrac{1}{3}=\dfrac{9}{24}-\dfrac{8}{24}=\dfrac{1}{24}\)
b, 3/5 + 4/7 + 2/8 + 10/25 + 9/21 + 28/16
= 3/5 + 4/7 + 2/8 + 2/5 + 3/7 + 14/8
= (3/5 + 2/5) + ( 4/7 + 3/7) + ( 2/8 + 14/8)
= 1 + 1 + 7/4
= 2 + 7/4 = 15/4
c , 8/7 + 7/6 + 5/8 + 10/12 + 24/28 + 6/16
= c , 8/7 + 7/6 + 5/8 + 5/6 + 6/7 + 1/2
= (8/7 + 6/7) + (7/6 + 5/6) + 5/8 + 1/2
= 14/7 + 12/6 + 5/8 + 1/2
= 2 + 2 + 5/8 + 1/2
= 4 + 9/8 = 41/8
\(a,\frac{2}{3}+\frac{1}{2}+\frac{1}{6}=\frac{4}{6}+\frac{3}{6}+\frac{1}{6}=\frac{8}{6}=\frac{4}{3}\)
\(b,\frac{5}{12}+\frac{5}{6}-\frac{3}{4}=\frac{5}{12}+\frac{10}{12}-\frac{9}{12}=\frac{6}{12}=\frac{1}{2}\)
a) 2/3 + 1/2 + 1/6 = 4/6 + 3/6 + 1/6 = 7/6 + 1/6 = 8/6 = 4/3
b) 5/12 + 5/6 - 3/4 = 5/12 + 10/12 - 9/12 = 15/12 - 9/12 = 6/12 = 1/2
c) 1/3 x 3/5 x 2/5 = 3/15 x 2/5 = 6/75 = 2/25
d) 15/16 : 3/8 x 3/4 = 15/16 x 8/3 x 3/4 = 1/10 x 3/4 = 3/40