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Sure=)
Simple task:)
Tính bằng cách thuận tiện nhất :
3/7 + 1/8 + 4/7 + 7/8
a. 2
b. 1 + 1
c. 2 + 1
d. ( 3/7 + 1/8 ) + ( 4/7 + 7/8 )
e. 3
g. 1 + 2
h. ( 3/7 + 4/7 ) + ( 1/8 + 7/8 )
1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9=135
\(\frac{1}{2}+\frac{1}{3}=\frac{1.3}{2.3}+\frac{1.2}{2.3}=\frac{3}{6}+\frac{2}{6}=\frac{5}{6}\)
\(\frac{7}{8}+\frac{2}{9}=\frac{63}{72}+\frac{16}{72}=\frac{79}{72}\)
\(\frac{17}{9}-\frac{11}{9}=\frac{6}{9}=\frac{2}{3}\)
\(\frac{1}{2}:\frac{1}{3}=\frac{1}{2}.\frac{3}{1}=\frac{3}{2}\)
\(\frac{1}{8}x\frac{7}{8}=\frac{7}{64}\)
Ủng hộ nhé !
a) \(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}\)
\(=1-\frac{1}{4}\)
\(=\frac{3}{4}\)
b) \(\frac{4}{7}\times\frac{8}{9}+\frac{4}{7}\times\frac{1}{9}\)
\(=\frac{4}{7}\times\left(\frac{8}{9}+\frac{1}{9}\right)\)
\(=\frac{4}{7}\times1\)
\(=\frac{4}{7}\)
c) \(\frac{13}{6}\times\frac{3}{8}-\frac{3}{8}\times\frac{7}{6}\)
\(=\frac{3}{8}\times\left(\frac{13}{6}-\frac{7}{6}\right)\)
\(=\frac{3}{8}\times1\)
\(=\frac{3}{8}\)
d) \(\frac{1}{1x2}+\frac{1}{2x3}+\frac{1}{3x4}+...+\frac{1}{9x10}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\)
\(=1-\frac{1}{10}\)
\(=\frac{9}{10}\)
1+1=2
2+2=4
3+3=6
4+4=8
5+5=10
6+6=12
7+7=14
8+8=16
9+9=18
1+2+3+4+5+6+7+8+9=45
mk nhanh nhất
1+1=2
2+2=4
3+3=6
4+4=8
5+5=10
6+6=12
7+7=14
8+8=16
9+9=18
1+2+3+4+5+6+7+8+9=45 k nha
1 + 9 + 3 + 7 + 5 + 8 + 4 + 6 + 2 + 1 + 2 + 3 + 4 + 5 + 7 + 8 + 6 + 9 = 90
\(\dfrac{2}{1}\)-\(\dfrac{7}{8}\)
=\(\dfrac{16}{8}\)-\(\dfrac{7}{8}\)= \(\dfrac{9}{8}\)
=16/8-7/8
=9/8