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Bài 2:
\(B=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right).......\left(1-\frac{1}{2004}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}....\frac{2003}{2004}\)
\(=\frac{1}{2004}\)
\(\frac{5}{1.6}\)+ \(\frac{5}{6.11}\)+ .........+\(\frac{5}{501.506}\)
=\(\frac{1}{1.6}+\frac{1}{6.11}+.....+\frac{1}{501.506}\)
=\(\frac{1}{1}-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+......+\frac{1}{501}-\frac{1}{506}\)
=\(\frac{1}{1}-\frac{1}{506}\)
= tự tính nha
P = \(\left(\frac{13}{84}\times1\frac{2}{5}-2\frac{1}{2}\times\frac{7}{180}\right):2\frac{7}{18}+4\frac{1}{2}\times\frac{1}{10}\)
P = ( 13/84 x 7/5 - 5/2 x 7/180 ) : 43/18 + 9/2 x 1/10
P = ( 13/60 - 7/72 ) : 43/18 + 9/20
P = 43/360 : 43/18 + 9/20
P = 43/360 x 18/43 + 9/20
P = 1/20 + 9/20
P = 1/2
a,11/5x3/2-3/1/2x3/5
=11/2x3/5-7/2-3/5
=3/5x(11/2-7/2)
=3/5x2
=6/5
b,(1/2-1/3+1/4-1/5):(1/4-1/6)
=(1/6+1/20):1/12
=13/60:1/2
=13/30
a.
2,52 : 0,56. 7,2 :2,5
= 4,5 . 7,2 : 2,5
= 32,4 : 2,5
= 12,96
b.
\(\frac{5}{13}\times\left(\frac{54}{20}-\frac{1}{10}\right)+3\frac{2}{5}\)
= \(\frac{5}{13}\times\left(\frac{27}{10}-\frac{1}{10}\right)+\frac{17}{5}\)
= \(\frac{5}{13}\times\frac{13}{5}+\frac{17}{5}\)
= \(1+\frac{17}{5}=\frac{22}{5}\)
Tính giá trị của biểu thức:
a ) 2,52 : 0,56 . 7,2 :2,5
= 4,5 . 7,2 : 2,5
= 32,4 : 2,5
= 12,96
b )
\(\frac{5}{13}\)\(\times\)\(\left(\frac{54}{20}-\frac{1}{10}\right)\)\(+\)\(3\frac{2}{5}\)
\(=\)\(\frac{5}{13}\)\(\times\)\(\left(\frac{54}{20}-\frac{2}{20}\right)\)\(+\)\(\frac{17}{5}\)
\(=\)\(\frac{5}{13}\)\(\times\)\(\frac{52}{20}\)\(+\)\(\frac{17}{5}\)
\(=\)\(\frac{5}{13}\)\(\times\)\(\frac{13}{5}\)\(+\)\(\frac{17}{5}\)
\(=\)\(1\)\(+\)\(\frac{17}{5}\)
\(=\)\(\frac{22}{5}\)