Toán Lớp 6: Tính giá trị của biểu thức sau: A=(1+12).(1+1/3)…(1+1/2009)
B=(1-12).(1-1/3)…(1-1/1000)
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 6: Tính giá trị của biểu thức sau: A=(1+12).(1+1/3)…(1+1/2009)
B=(1-12).(1-1/3)…(1-1/1000)
Comments ( 2 )
1)A=(1 + $\dfrac{1}{2}$) . (1 + $\dfrac{1}{3}$) . … . (1 + $\dfrac{1}{2009}$)
A=$\dfrac{3}{2}$ . $\dfrac{4}{3}$ . … . $\dfrac{2010}{2009}$
A=$\dfrac{3.4. … .2010}{2.3. … 2009}$
A=$\dfrac{2010}{2}$=1005
Vậy A=1005
2)B=(1 – $\dfrac{1}{2}$) . ( 1 – $\dfrac{1}{3}$) . … . ( 1 – $\dfrac{1}{1000}$)
B=$\dfrac{1}{2}$ . $\dfrac{2}{3}$ . … . $\dfrac{999}{1000}$
B=$\dfrac{1 . 2 . … . 999}{2 . 3 . … . 1000}$
B=$\dfrac{1}{1000}$
Vậy B=$\dfrac{1}{1000}$