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3 tháng 1 2017

Ta có

\(A=\left(\frac{3}{4}-81\right)\left(\frac{3^2}{5}-81\right)...\left(\frac{3^6}{9}-81\right)...\left(\frac{3^{2013}}{2016}-81\right)=\left(\frac{3}{4}-81\right)\left(\frac{3^2}{5}-81\right)...\left(\frac{729}{9}-81\right)...\left(\frac{3^{2013}}{2016}-81\right)=0\)

vì 729/9=81

Vậy A=0

k me đi

3 tháng 1 2017

\(\left(\frac{3}{4}-81\right).\left(\frac{3^2}{5}-81\right).\left(\frac{3^3}{6}-81\right).\left(\frac{3^4}{7}-81\right).\left(\frac{3^5}{8}-81\right).\left(\frac{729}{9}-81\right)....\left(\frac{3^{2013}}{2016}-81\right)\)

=>....................................................................................................................(81-81)..............................................

=>.....................................................................................................................0.....................................................

=>A=0

9 tháng 1 2017

theo bài ra ta có:

\(C=\left(\frac{3}{4}-81\right)\left(\frac{3^2}{5}-81\right)\left(\frac{3^3}{6}-81\right)...\left(\frac{3^{2013}}{2016}-81\right)\)

C = \(\left(\frac{3}{4}-81\right)...\left(\frac{3^6}{9}-81\right)...\left(\frac{3^{2013}}{2016}-81\right)\)

\(C=\left(\frac{3}{4}-81\right)...\left(81-81\right)...\left(\frac{3^{2013}}{2016}-81\right)\)

C = \(\left(\frac{3}{4}-81\right)...0...\left(\frac{3^{2013}}{2016}-81\right)\)

C = 0

vậy C = 0

9 tháng 1 2017

thks

Đặt \(A=\left(\dfrac{3}{4}-81\right)\left(\dfrac{3^2}{5}-81\right)\left(\dfrac{3^3}{6}-81\right)\cdot...\cdot\left(\dfrac{3^{2000}}{2003}-81\right)\)

\(=\left(\dfrac{3^6}{9}-81\right)\cdot\left(\dfrac{3}{4}-81\right)\left(\dfrac{3^2}{5}-81\right)\cdot...\cdot\left(\dfrac{3^{2000}}{2003}-81\right)\)

\(=\left(81-81\right)\cdot\left(\dfrac{3}{4}-81\right)\left(\dfrac{3^2}{5}-81\right)\cdot...\cdot\left(\dfrac{3^{2000}}{2003}-81\right)\)

=0