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37 x 13 - \(\frac{13}{24}\) + 37 x 12
= 37 x ( 13 + 12) - \(\frac{13}{24}\)
= 37 x 25 - \(\frac{13}{24}\)
= 925 - \(\frac{13}{24}\)
= \(\frac{22187}{24}\)
a)<=>2/7:(13/24+5/24) b)<=>15/24-9/24-4/24 c)=7.5.39/13.14.15
<=>2/7:3/4 <=>2/24=1/12 =3/2.3
<=>2/7x4/3 =1/2
<=>8/21
a. \(\frac{2}{7}:\frac{13}{24}+\frac{2}{7}:\frac{5}{24}\)
= \(\frac{2}{7}:\left(\frac{13}{24}+\frac{5}{24}\right)\)
= \(\frac{2}{7}:\frac{3}{4}\)
= \(\frac{8}{21}\)
b. \(\frac{15}{24}-\frac{3}{8}-\frac{1}{6}\)
= \(\frac{15}{24}-\frac{9}{24}-\frac{4}{24}\)
= \(\frac{2}{24}=\frac{1}{12}\)
c. \(\frac{7}{13}.\frac{5}{14}.\frac{39}{15}\)
= \(\frac{7.5.3.13}{13.2.7.3.5}\)
= \(\frac{1}{2}\)
\(=\frac{4}{2x4}+\frac{4}{4x6}+\frac{4}{6x8}+...+\frac{4}{18x20}\)
\(=2\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+...+\frac{1}{18}-\frac{1}{20}\right)\)
\(=2x\left(\frac{1}{2}-\frac{1}{20}\right)\\ =2x\frac{9}{20}\\ =\frac{9}{10}\)
Đặt biểu thức trên là A ta có:
A = \(\frac{1}{3}\)+ \(\frac{1}{6}\)+ \(\frac{1}{12}\)+ \(\frac{1}{24}\)+ \(\frac{1}{48}\)+ \(\frac{1}{96}\)
A x 3 = \(1\)+ \(\frac{1}{2}\)+ \(\frac{1}{4}\)+ \(\frac{1}{8}\)+ \(\frac{1}{16}\)+ \(\frac{1}{32}\)
A x 3 = \(1\)+ \(1\)- \(\frac{1}{2}\)+ \(\frac{1}{2}\)- \(\frac{1}{4}\)+ \(\frac{1}{4}\)- \(\frac{1}{8}\)+ \(\frac{1}{8}\)- \(\frac{1}{16}\)+ \(\frac{1}{16}\)- \(\frac{1}{32}\)
A x 3 = 2 - \(\frac{1}{32}\)= \(\frac{63}{32}\)
A = \(\frac{63}{32}\): 3 = \(\frac{63}{96}\)
\(S=\frac{1}{2.4}+\frac{1}{4.6}+...+\frac{1}{20.22}\)
\(2S=\frac{2}{2.4}+\frac{2}{4.6}+...+\frac{2}{20.22}\)
\(2S=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+...+\frac{1}{20}-\frac{1}{22}\)
\(2S=1-\frac{1}{22}=\frac{21}{22}\)
\(S=\frac{21}{22}:2=\frac{21}{44}\)
a, \(\frac{1}{2}\)+ \(\frac{1}{3}\)+ \(\frac{1}{5}\)+ \(\frac{1}{6}\)
= (\(\frac{1}{2}+\)\(\frac{1}{3}+\)\(\frac{1}{6}\)) + \(\frac{1}{5}\)
= 1 + \(\frac{1}{5}\)
= \(\frac{6}{5}\)
b, mk chịu
a) \(\frac{1}{2}+\frac{1}{3}+\frac{1}{5}+\frac{1}{6}=\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{6}\right)+\frac{1}{5}\)
\(=\left(\frac{3}{6}+\frac{2}{6}+\frac{1}{6}\right)+\frac{1}{5}\)
\(=1+\frac{1}{5}\)
\(=\frac{6}{5}\)
b) \(\frac{4}{6}+\frac{7}{13}+\frac{17}{9}+\frac{19}{13}-\frac{8}{9}+\frac{14}{6}=\left(\frac{4}{6}+\frac{14}{6}\right)+\left(\frac{7}{13}+\frac{19}{13}\right)+\left(\frac{17}{9}-\frac{8}{9}\right)\)
\(=\frac{18}{6}+\frac{26}{13}+\frac{9}{9}=3+2+1=6\)
1, =35 x 77-35 x 12+35x35-35 x 18 suy ra =35 x(77-12+35-18)=35 x 82=2870.
2, =2014 x (100-1)=201400-2014=199386.
3,=35x12+65x12+65=12x(65+35)+65=1200+65=1265.
4.=\(\frac{13\times\left(37-1\right)}{12\times\left(37+2\right)}\)=\(\frac{13\times36}{12\times39}=\frac{13\times3\times12}{12\times3\times13}=1\)
tck nha bạn