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a: \(=\left(1+\dfrac{4}{23}-\dfrac{4}{23}\right)+\left(\dfrac{5}{21}+\dfrac{16}{21}\right)+\dfrac{1}{2}\)
\(=1+1+\dfrac{1}{2}=2+\dfrac{1}{2}=\dfrac{5}{2}\)
b: \(=\left(\dfrac{1}{25}+\dfrac{5}{25}+\dfrac{25}{25}\right):\left(\dfrac{1}{25}-\dfrac{5}{25}-\dfrac{25}{25}\right)\)
\(=\dfrac{31}{25}:\dfrac{-29}{25}=\dfrac{-31}{29}\)
c: \(=\dfrac{\dfrac{1}{9}-\dfrac{1}{7}-\dfrac{1}{11}}{\dfrac{4}{9}-\dfrac{4}{7}-\dfrac{4}{11}}+\dfrac{\dfrac{3}{5}-\dfrac{3}{25}-\dfrac{3}{125}-\dfrac{3}{625}}{\dfrac{4}{5}-\dfrac{4}{25}-\dfrac{4}{125}-\dfrac{4}{625}}\)
=1/4+3/4
=1
\(a,\dfrac{2^4.6^7}{9^3.4^6}=\dfrac{2^4.\left(2.3\right)^7}{\left(3^2\right)^3.\left(2^2\right)^6}=\dfrac{2^4.2^7.3^7}{3^6.2^{12}}=\dfrac{2^{11}.3^7}{3^6.2^{12}}=\dfrac{3}{2}\)
\(b,\dfrac{3^{18}.24^4}{9^4.81^5}=\dfrac{3^{18}.\left(3.2^3\right)^4}{\left(3^2\right)^4.\left(3^4\right)^5}=\dfrac{3^{18}.3^4.2^{12}}{3^8.3^{20}}=\dfrac{3^{22}.2^{12}}{3^{28}}=\dfrac{2^{12}}{3^8}\)
\(\frac{-1}{12}-\left(2\frac{5}{8}-\frac{1}{3}\right)\)
\(=\frac{-1}{12}-\left(\frac{21}{8}-\frac{1}{3}\right)\)
\(=\frac{-1}{12}-\left(\frac{63}{24}-\frac{8}{24}\right)\)
\(=\frac{-1}{12}-\frac{55}{24}\)
\(=\frac{-2}{24}-\frac{55}{24}\)
\(=\frac{-19}{8}\)
1 + 5 + 52 + 53 + 54 + ....+ 52015
Đặt A= 1 + 5 + 52 + 53 + 54 + ....+ 52015
5A= 5 ( 1 + 5 + 52 + 53 + 54 + ....+ 52015)
5A= 5 + 52 + 53 + 54 + ....+ 52015+52016
5A- A= ( 5 + 52 + 53 + 54 + ....+ 52015+52016) -( 1 + 5 + 52 + 53 + 54 + ....+ 52015)
4A= 52016-1
A= (52016-1) :4
Vậy...
15^3+5.15^2-5^3 / 18^3+6.18^2-6^3
=3375+5.225-125 /5832+6.324-216
=3375+1125-125 /5832+1944-216
=4500-125 /7826-216
=4375 /7610
=875 /1522
mk ko bt viết phần nên viết phần bằng dấu gạch / nhé.mk cx ko bt đúng hay sai đâu nhé
\(\dfrac{17539}{8}\)