C=1/1*2+1/3*4+....+1/99*100
D=1/51*100+1/52*99+.....+1/100*51
chung minh c:d ko co gia tri la so tu nhien
a)so sanh E=2018^99-1/2018^100-1 va F=2018^98/2018^99-1
b)Tim so nguyen to ab (a>b>0),biet ab-ba la so chinh phuong
c)Cho abc la so tu nhien co 3 chu so .Tim gia tri lon nhat cua A={abc/a+b+c}+1918
So sanh phan so 1313/9191va1111/7373
Chung minh rang
A=1/12+1/13+.....+1/22>1/2
B=1/10+1/11+.....+1/99+1/100>1
C=1/5+1/6+1/7+....+1/17<2
D=3/10+3/11+3/12+3/13+3/14
Hoi d co la so tu nhien ko
Cam on cac ban rat nhieu
Chứng Minh:
1/1*2+1/3*4+1/5*6+...+1/97*98+1/99*100=1/51+1/52+1/53+...+1/99+1/100
Chứng minh rằng
1- 1/2+ 1/3- 1/4+...+ 1/99- 1/100= 1/51+ 1/52+...+ 1/100= -1/2
\(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+.....+\frac{1}{99}-\frac{1}{100}\)= \(\left(1+\frac{1}{3}+....+\frac{1}{99}\right)-\left(\frac{1}{2}+\frac{1}{4}+....+\frac{1}{100}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+....+\frac{1}{99}+\frac{1}{100}\right)\)\(-2\left(\frac{1}{2}+\frac{1}{4}+....+\frac{1}{100}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+....+\frac{1}{99}+\frac{1}{100}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+....+\frac{1}{50}\right)\)
\(\frac{1}{51}+\frac{1}{52}+....+\frac{1}{100}=-\frac{1}{2}\)
tôi xem sex
A = 1 . 2 + 2 . 3 + 3 . 4 + ......... + 98 . 99 / 1 + ( 1 + 2 ) + ( 1 + 2 + 3 ) + ........... + ( 1 + 2 + 3 + ...... + 98 )
B = ( 1 / 51 . 52 ) + 1 / 52 . 53 + ...... + 1 / 100 . 101 ) : ( 1 / 1 . 2 + 1 / 2 . 3 + ........ + 1 / 99 . 100 + 1 / 100 . 101
Chứng minh rằng :
a,1- 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + ...... + 1/ 99 - 1/ 100 = 1 / 51 + 1/ 52 + 1/ 53 + ... + 1/ 100
b, A= 1/3 - 2/ 32 + 3/ 33 - 4/ 34 + .... + 99/ 399 - 100/ 3100 < 3/ 16
\(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}=\left(1+\frac{1}{3}+\frac{1}{5}+...+\frac{1}{99}\right)-\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{100}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{99}+\frac{1}{100}\right)-2\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{6}+...+\frac{1}{100}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{100}\right)-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{50}\right)=\frac{1}{51}+\frac{1}{52}+...+\frac{1}{100}\)
\(\RightarrowĐPCM\)
TINH GIA TRI CUA BIEU THUC
a: A=100-99+98-97....+4 -3 +2=.......
b:B =1+1+1+.......+1 -999(CO 1000 SO 1)=.......
Chứng minh :(1+1/3+1/5+...+1/99)-(1/2+1/4+1/6+...+1/100)=1/51+1/52+1/53+...+1/100
Chứng minh: 1- 1\2 + 1\3 - 1\4 + 1 \5 - 1\6 + ....... + 1\99 -1\100 = 1\51 + 1\52 + 1\53 + ..........+1\100
đây là j`? đầu đề hổng có, làm sao mà giải đc?????