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\(\frac{1}{2}\cdot\frac{18}{14}+\frac{1}{2}\cdot\frac{3}{14}-\frac{1}{2}\cdot\frac{7}{14}\)
\(=\frac{1}{2}\left(\frac{18}{14}+\frac{3}{14}-\frac{7}{14}\right)\)
\(=\frac{1}{2}\cdot1=\frac{1}{2}\)
\(\frac{3}{5}\times\frac{6}{7}+\frac{3}{5}:7+\frac{6}{5}\)
\(=\frac{3}{5}\times\frac{6}{7}+\frac{3}{5}\times\frac{1}{7}+\frac{6}{5}\)
\(=\frac{3}{5}\times\left(\frac{6}{7}+\frac{1}{7}\right)+\frac{6}{5}\)
\(=\frac{3}{5}\times1+\frac{6}{5}\)
\(=\frac{3}{5}+\frac{6}{5}=\frac{9}{5}\)
~ Hok tốt ~
\(\frac{29}{12}:\frac{1}{2}-\frac{5}{12}:\frac{1}{2}-\frac{1}{2}\)
\(=\left(\frac{29}{12}-\frac{5}{12}\right):\frac{1}{2}-\frac{1}{2}\)
\(=2:\frac{1}{2}-\frac{1}{2}\)
\(=4-\frac{1}{2}=\frac{7}{2}\)
~ Hok tốt ~
a) 145 + 86 + 14 + 55 = ( 145 + 55 ) + (86 + 14 )
= 200 + 100
= 300
b) 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = ( 1+9 +2 + 8) + ( 3 + 7 + 4 + 6 ) + 5
= 20 + 20 + 5
= 45
3 x 7/10 + 7/10 x 5 + 2 x 14/20
=3x7/10+7/10x5+2x7/10
=7/10x(3+5+2)
=7/10x10
=7
\(=\frac{10}{11}-\frac{3}{7}:\frac{7}{15}:\frac{15}{14}\)
\(=\frac{10}{11}-\frac{45}{49}:\frac{15}{14}\)
\(=\frac{10}{11}-\frac{6}{7}=\frac{70}{77}-\frac{66}{77}=\frac{4}{77}\)
10/7+9/27+8/14+5/3
=10/7+1/3+4/7+5/3
=(10/7+4/7)+(1/3+5/3)
=14/7+6/3
=2+2
=4