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Câu a) \(\dfrac{31995-81}{42660-108}=\dfrac{31914}{42552}=\dfrac{31914:10638}{42552:10638}\)
=\(\dfrac{3}{4}\)
Câu b) \(\dfrac{\left(3.5.7.11.13.15.37-10101\right)}{121212+40404}\)
=\(\dfrac{\left(3.5.7.11.13.15.37-3.7.13.37\right)}{3.7.13.37.12+3.7.13.37.4}\)
=\(\dfrac{3.7.13.37\left(5.11.15-1\right)}{3.7.13.37\left(12+4\right)}\)
= \(\dfrac{824}{16}\)=\(\dfrac{103}{2}\)
A = \(\frac{3^4\left(5.79-1\right)}{2^2.3^2\left(5.79-1\right)}=\frac{9}{4}\); B = \(\frac{3.7.13.37\left(5.11-1\right)}{4.3.7.13.37\left(3.5-1\right)}=\frac{54}{4.14}=\frac{2.9}{4.2.7}=\frac{9}{28}\)
31995 - 81 / 42660 - 108
= 31914 / 42552
= 3.10638 / 4.10638
= 3/4
A) 31995-81/ 42660- 108
= 31914/42552
= 3/4
B) 7.2.7.52/ 14.2.5
= 14 . 7 . 25 / 140
= 98 . 25/140
= 2450/140
= 35/2
C) 2^2 . 3^3 . 5/ 3.2^3.5^3
= 4 . 27 . 5 / 3 . ( 2 . 5 )3
= 108 . 5 / 3. 103
= 540 / 3000
= 9/50
\(A=\frac{4157-19}{12471-57}\)\(=\frac{4138}{12414}\)\(=\frac{4138:4138}{12414:4138}\)\(=\frac{1}{3}\)
\(B=\frac{7}{10^2+8.10^2}\)\(=\frac{7}{100+8.100}\)\(=\frac{7}{100+800}\)\(=\frac{7}{900}\)
\(C=\frac{31995}{42660-108}\)\(=\frac{31995}{42552}\)\(=\frac{31995:27}{42552:27}\)\(=\frac{1185}{1576}\)
\(D=\frac{2^{45}.5^3.2^6.3}{8.2^{18}.81.5}=\frac{2^{51}.5^3.3}{2^3.2^{18}.3^4.5}=\frac{2^{51}.5^3.3}{2^{21}.3^4.5}=\frac{2^{30}.5^2}{3^3}\)
k mình nhé.
A=4138/12414=1/3
B=7/900
C=31995/42552=1185/1576
Phần D tui chịu, ahihi
\(\frac{3}{2}\times\frac{4}{3}\times\frac{5}{4}\times...\times\frac{1000}{999}\)
\(=\frac{3\times4\times5\times...\times1000}{2\times3\times4\times...\times999}=\frac{1000}{2}=500\)
Sửa đề \(\frac{7}{2.5}\) phải là\(\frac{7}{3.5}\)
Ta có :
\(S=\frac{7}{3.5}+\frac{7}{5.7}+...+\frac{7}{997.999}\)
\(\Leftrightarrow\frac{2}{7}S=\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{997.999}\)
\(\Leftrightarrow\frac{2}{7}S=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{997}-\frac{1}{999}\)
\(\Leftrightarrow\frac{2}{7}S=\frac{1}{3}-\frac{1}{999}=\frac{332}{999}\)
\(\Leftrightarrow S=\frac{\frac{332}{999}}{\frac{2}{7}}=\frac{332}{999}\cdot\frac{7}{2}=\frac{1162}{999}\)
Cho mk hỏi là cậu lấy 2 ở đâu để làm tử hay là cậu thử
\(\frac{31995-81}{42660-108}=\frac{3}{4}\)
\(\frac{31995-81}{42660-108}\)
\(=\frac{31914}{42554}\)
\(=\frac{3}{4}\)
Vậy ...........................................