1/5x4/7+3/7x1/5-1/5
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1/2x1/3+1/3x1/4+1/4x1/5+1/5x1/6+1/6x1/7+1/7x1/8+1/8x1/9
=7/18
\(=\dfrac{3}{7}\times\left(\dfrac{1}{5}+\dfrac{2}{3}-\dfrac{1}{8}\right)\\ =\dfrac{3}{7}\times\left(\dfrac{24}{5\times24}+\dfrac{2\times40}{3\times40}-\dfrac{15}{8\times15}\right)\\ =\dfrac{3}{7}\times\left(\dfrac{24+80-15}{120}\right)\\ =\dfrac{3}{7}\times\dfrac{89}{120}\\ =\dfrac{89}{280}\)
\(\dfrac{3}{7}\times\dfrac{1}{5}+\dfrac{2}{3}\times\dfrac{3}{7}-\dfrac{3}{7}\times\dfrac{1}{8}\)
\(=\dfrac{3}{7}\times\left(\dfrac{1}{5}+\dfrac{3}{7}-\dfrac{1}{8}\right)\)
\(=\dfrac{3}{7}\times\dfrac{56+120-35}{280}\)
\(=\dfrac{3}{7}\times\dfrac{141}{280}\)
\(=\dfrac{423}{1960}\)
a) C1:
= 11/10 x 4/5 = 44/50 = 22/25
C2:
= 3/5 x 4/5 + 1/2 x 4/5 = 12/25 + 2/5 = 22/25
b) C1:
= 2/5 x (3/7 + 4/7) = 2/5 x 1 = 2/5
C2:
= 6/35 + 8/35 = 14/35 = 2/5
a)(3/5+1/2)x4/5
= \(\left(\dfrac{6}{10}+\dfrac{5}{10}\right)\times\dfrac{4}{5}=\dfrac{11}{10}\times\dfrac{4}{5}=\dfrac{22}{25}\)
\(=\dfrac{3}{5}\times\dfrac{4}{5}+\dfrac{1}{2}\times\dfrac{4}{5}=\dfrac{12}{25}+\dfrac{2}{5}=\dfrac{22}{25}\)
b)2/5x3/7+2/5x4/7
\(=\dfrac{6}{35}+\dfrac{8}{35}=\dfrac{14}{35}=\dfrac{2}{5}\)
\(=\dfrac{2}{5}\times\left(\dfrac{3}{7}+\dfrac{4}{7}\right)=\dfrac{2}{5}\times1=\dfrac{2}{5}\)
\(\)
\(\dfrac{1}{5}\times\dfrac{4}{7}+\dfrac{3}{7}\times\dfrac{1}{5}-\dfrac{1}{5}\)
\(=\dfrac{4}{35}+\dfrac{3}{35}-\dfrac{1}{5}\)
\(=\dfrac{7}{35}-\dfrac{1}{5}\)
\(=\dfrac{1}{5}-\dfrac{1}{5}\)
\(=0\)
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