Tính A = \(\left(1^3-1000\right)\cdot\left(2^3-1000\right)\cdot...\cdot\left(2018^3-1000\right)\).Kb vs mik nha! ...
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Trong biểu thức trên có chứa (1000-103), mà (1000-103)=1000-1000=0
Do đó tích trên bằng 0
\(\left(1000-1^3\right)\left(1000-2^3\right)\left(1000-3^3\right)...\left(1000-10^3\right)...\left(1000-50^3\right)\)
\(=\left(1000-1^3\right)\left(1000-2^3\right)\left(1000-3^3\right)...\left(1000-1000\right)...\left(1000-50^3\right)\)
\(=\left(1000-1^3\right)\left(1000-2^3\right)\left(1000-3^3\right)...\cdot0\cdot\left(1000-50^3\right)\)
\(=0\)
#)Giải :
a)\(2009^{\left(1000-1^3\right)\left(1000-2^3\right)...\left(1000-15^3\right)}=2009^{\left(1000-1^3\right)...\left(1000-10^3\right)...\left(1000-15^3\right)}=2009^0=1\)
b)\(\left(\frac{1}{125}-\frac{1}{1^3}\right)\left(\frac{1}{125}-\frac{1}{2^3}\right)...\left(\frac{1}{125}-\frac{1}{25^3}\right)=\left(\frac{1}{125}-\frac{1}{1^3}\right)...\left(\frac{1}{125}-\frac{1}{5^3}\right)...\left(\frac{1}{125}-\frac{1}{25^3}\right)=\left(\frac{1}{125}-\frac{1}{1^3}\right)...0...\left(\frac{1}{125}-\frac{1}{25^3}\right)=0\)
\(2009^{\left(1000-1^3\right).\left(1000-2^3\right)...\left(1000-15^3\right)}\)
= \(2009^{\left(1000-1^3\right).\left(1000-2^3\right)...\left(1000-10^3\right)..\left(1000-15^3\right)}\)
= \(2009^{\left(1000-1^3\right).\left(1000-2^3\right)...\left(1000-1000\right)..\left(1000-15^3\right)}\)
= \(2009^{\left(1000-1^3\right).\left(1000-2^3\right)...0..\left(1000-15^3\right)}\)
= \(2009^0\)
= \(1\)
1,
\(A=\left(\dfrac{1}{2}-1\right)\cdot\left(\dfrac{1}{3}-1\right)\cdot...\cdot\left(\dfrac{1}{2018}-1\right)\\ A=\left(-\dfrac{1}{2}\right)\cdot\left(-\dfrac{2}{3}\right)\cdot...\cdot\left(-\dfrac{2017}{2018}\right)\\ =-\left(\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot...\cdot\dfrac{2017}{2018}\right)\\ =-\dfrac{1}{2018}\)
= (1/2).(2/3).(4/5).(5/6)......(2016/2017).(2017/2018)
=1.2.3.4.5......2016.2017/2.3.4.5.....2017.2018
=1/2018
\(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)\cdot\cdot\cdot\cdot\cdot\left(1-\frac{1}{2017}\right)\left(1-\frac{1}{2018}\right)\)
\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\cdot\cdot\cdot\cdot\frac{2016}{2017}\cdot\frac{2017}{2018}\)
\(=\frac{1\cdot2\cdot3\cdot\cdot\cdot\cdot\cdot2016\cdot2017}{2\cdot3\cdot4\cdot\cdot\cdot\cdot2017\cdot2018}\)
\(=\frac{1}{2018}\)
\(A=\)\(\left(1^3-1000\right).\left(2^3-1000\right)\)\(.....\left(2018^3-1000\right)\)
\(A=\left(1^3-1000\right).\left(2^3-1000\right)...\left(10^3-1000\right)...\left(2018^3-1000\right)\)
\(A=\left(1^3-1000\right).\left(2^3-1000\right)...0...\left(2018^3-1000\right)\)
\(A=0\)
~~~Hok tốt~~~