Rút gọn :
A = \(\frac{4157-19}{12471-57}\)
B = \(\frac{7}{10^2+8.10^2}\)
C = \(\frac{31995}{42660-108}\)
D = \(\frac{2^{45}.5^3.2^6.3}{8.2^{18}.81.5}\)
Ai làm đầy đủ , chi tiết , tui tk 10 lần .
Nhanh lên nhé ! 1h tui đi học rùi !
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A = \(\frac{3^4\left(5.79-1\right)}{2^2.3^2\left(5.79-1\right)}=\frac{9}{4}\); B = \(\frac{3.7.13.37\left(5.11-1\right)}{4.3.7.13.37\left(3.5-1\right)}=\frac{54}{4.14}=\frac{2.9}{4.2.7}=\frac{9}{28}\)
A = \(\frac{2^{13}.5^2.2^6.3^4}{8.2^{18}.81.5}\)
= \(\frac{2^{19}.5^2.3^4}{2^3.2^{18}.3^4.5}\)
= \(\frac{2^{19}.5^2.3^4}{2^{21}.3^4.5}\)
= \(\frac{5}{2^2}\) = \(\frac{5}{4}\)
\(A=\frac{2^{13}.5^2.2^6.3^4}{8.2^{18}.81.5}\)
\(A=\frac{2^{19}.5^2.3^4}{2^{21}.3^4.5}=\frac{5}{2^3}=\frac{5}{8}\)
\(D=\frac{\frac{88}{132}-\frac{33}{132}+\frac{60}{132}}{\frac{55}{132}+\frac{132}{132}-\frac{84}{132}}\)
\(D=\frac{\frac{115}{132}}{\frac{103}{132}}\)
\(D=\frac{115}{103}\)
Ta có: \(\frac{3}{1^2.2^2}=\frac{3}{1.4}=1-\frac{1}{4}\); \(\frac{5}{2^2.3^2}=\frac{5}{4.9}=\frac{1}{4}-\frac{1}{9}\); \(\frac{7}{3^2.4^2}=\frac{7}{9.16}=\frac{1}{9}-\frac{1}{16}\); ...; \(\frac{39}{19^2.20^2}=\frac{39}{361.400}=\frac{1}{361}-\frac{1}{400}\)
Gọi tổng đó là A => A=\(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{9}+\frac{1}{9}-\frac{1}{16}+...+\frac{1}{361}-\frac{1}{400}\)
=> \(A=1-\frac{1}{400}=\frac{399}{400}< \frac{400}{400}=1\)
=> A < 1
\(\frac{2^2.3^3.5^7}{2^3.3^4.5^6}=\frac{1.1.5}{2.3.1}=\frac{5}{6}\)
Làm tương tự
to noi that: nguoi ta chi thich giup lam bai kho thoi chu bai nay ai di hoc cung lam dc
tai sao ban phai hoi
\(A=\frac{4157-19}{12471-57}\)\(=\frac{4138}{12414}\)\(=\frac{4138:4138}{12414:4138}\)\(=\frac{1}{3}\)
\(B=\frac{7}{10^2+8.10^2}\)\(=\frac{7}{100+8.100}\)\(=\frac{7}{100+800}\)\(=\frac{7}{900}\)
\(C=\frac{31995}{42660-108}\)\(=\frac{31995}{42552}\)\(=\frac{31995:27}{42552:27}\)\(=\frac{1185}{1576}\)
\(D=\frac{2^{45}.5^3.2^6.3}{8.2^{18}.81.5}=\frac{2^{51}.5^3.3}{2^3.2^{18}.3^4.5}=\frac{2^{51}.5^3.3}{2^{21}.3^4.5}=\frac{2^{30}.5^2}{3^3}\)
k mình nhé.
A=4138/12414=1/3
B=7/900
C=31995/42552=1185/1576
Phần D tui chịu, ahihi