Cho tích :A=1/2x3/4x5/6x7/8x...x79/80 .CMR A <1/9
Tính: 1/2x3/4x5/6x7/8x...x79/80 .CMR A
PLEASE HELP, HELP!!!!!
So sánh A=1/2x3+1/4x5+1/6x7+.....+1/18.19 và B=9/19
C=1/2x3/4x5/6x7/8x.....x199/200
D=1/4x2/6x3/8x4/10x......x30/62x31/64
Cho: A = 1/2x3/4x5/6x.......x99/100
B = 2/3x4/5x5/6x7/8x....100/101
a/ CM A< B
b/CM : A<1
A= 1/1x2 x 4/2x3 x 9/3x4 x 16/4x5 x 25/5x6 x 36/6x7
Đây là bài tính hợp lý ạ , cảm ơn
1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+.....+1/11x12
cho S = 1/2x3+1/4x5+1/6x7+....+1/2020x2021+1/2022x2023
So sánh S với 1011/2023
\(\frac{1}{2x3}+\frac{1}{4x5}+\frac{1}{6x7}+\frac{1}{8x9}+\frac{1}{1x10}\)