Tính giá trị của biểu thức :\(A=\dfrac{1}{2}.\left(1+\dfrac{1}{1.3}\right)\left(1+\dfrac{1}{2.4}\right)\left(1+\dfrac{1}{3.5}\right)....\left(1+\dfrac{1}{2019.2021}\right)\)
24/1.3.5+24/3.5.7+24/5.7.9+...+24/25.27.29
24/1.3.5+24/3.5.7+24/5.7.9+...+24/25.27.29
Tính: M= 1/1.3.5+1/3.5.7+1+....+1/95.97.99
A=24/1.3.5+24/3.5.7+24/5.7.9+...+24/25.27.29
A=24/1.3.5+24/3.5.7+24/5.7.9+...+24/25.27.29
Chứng minh 1.3.5.....1997+2.4.6.....1998 chia hết cho 1999
C/M:
1.3.5....1997-2.4.6...1998 chia hết cho 1999
chứng minh rằng tổng: 1.3.5.....1997+2.4.6.....1998 chia hết cho 1999