\(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)\left(1-\frac{1}{5}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}\)
\(=\frac{1.2.3.4}{2.3.4.5}\)
\(=\frac{1}{5}\)
\(\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)\left(1-\frac{1}{5}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}\)
\(=\frac{1.2.3.4}{2.3.4.5}\)
\(=\frac{1}{5}\)
1. (1+1/2).(1+1/2^2).(1+1/2^3)....(1+1/2^100) < 3
2. 1/(5+1)+2/(5^2+1)+4/(5^4+1)+...+ 1024/(5^1024+1) <1/4
3. 3/(1!+2!+3!)+4/(2!+3!+4!)+...+100/(98!+99!+100!) <1/2
a,1/3 .(x-2/5)=3/4 b, 7/3:(x-2/3)=4/5 c,1/3.(x-2/5)=4/5 d, 2/3.(x-1/2)-1/4.(x-2/5)=7/3 e,3/7 .(x-2/3)+1/2=5/4.(x-2) f,1/2.(x-3)+1/3.(x-4)+1/4.(x-5)=1/5 g,[2/3.(x-1/2)-4/5]:(x-1/3)=21/5 h, {x-[1/2.(x-3)+11/5]}:(x-1/2)=3/5 i,x.(x-2/5)-(x+2).x+11/4=4/3
a) 4 3/8 + 5 2/3 b) 2 3/8 + 1 1/4 + 3 6/7
c) 2 3/8 - 1 1/4 + 5 1/3 d) (5/2 + 1/3) : ( 1 - 1/2)
e) (5/2 - 1/3) x 9/2 - 6/7
1. a,23/27-(11/17-4/27) +(28/17) b,2/3 .7/9 +2/3 .2/9-2/9 c,7/3:5/11-1/3.11/5 d,(1+1/2) .(1+1/3) .(1+1/4).......(1+1/2023) e, (1-1/2).(1-1/3).....(1-1/2023) f,13/17.5/11-7/13.2/5+5/11.4/17-2/5.6/13 g, 1/2+1/3.1/4-1/5:1/6 2,so sánh n+2/n+3 và n+1/n+2 ( n là số tự nhiên)
1. 3/2 x 4/5 - x = 2/3
2.x x3 1/2=3 1/3 : 4 1/4
3. 5 2/3:x = 3 2/3- 2 1/2
4. 3/2+1/2:x=3 1/2
5.3/4 x x - 1/5=1/5:1/8
Cho dãy : 1/1 ; 2/1 ; 1/2 ; 3/1 ; 2/2 ; 1/3 ; 4/1 ; 3/2 ; 2/3 ; 1/4 ; 5/1 ; 4/2 ; 3/3 ; 2/4 ; 1/5 ;... . Tìm số thứ 2001 của dãy
tính
a, 1/2-1/3+1/3-1/4+1/4-1/5
b, 1/3-1/5+1/5-1/7+1/7-1/0
c, 3/4-1/3-1/6
d, 1/2-1/3+1/4-1/6
a,-2\3x+1\5=1\10
b,2|1\2x-3\8|-3\2=1\4
c,-5(x+1\5)-1\2(x-2\3)=3\2x-5\6
d,3(x-1\2)- 5(x+3\5)=-x+1\5
e,3\4-2.|2x-0,125|=2
f,2|1\2x-1\3|-3\2=1\4
g,4\5-1\2x=1\10
A= ( 6 : 3/5 - 1 1/6 x 6/7 ) : ( 4 1/5 x 10/11 + 5 2/11 )
B= ( 1 - 1/2 ) x ( 1- 1/4 ) x ... x ( 1 - 1/2003 ) x ( 1 - 1/2004 )
C= 5 9/10 : 3/2 - ( 2 1/3 x 4 1/2 - 2 x 2 1/3 ) : 7/4
Tính giá trị biểu thức
a) (1-1/2).(1-1/3).(1-1/4)...(1-1/20)
b) 1+1/2+1/2^2+1/2^3+...+1/2^2012
c)7/4.(3333/1212+3333/2020+3333/3030+33334242)
d)2/3-1/4+5/11/5/12+1-7/11
e) 3/5+3/7-3/11/4/5+4/7-4/11