tính giá trị biểu thức sau:a) A=(1-1/2)x(1-1/3)x(1-1/4)x(1-1/5)...............................(1-1/2003)x(1-1/2004)
b) B=5 9/10:3/2-(2 1/3x4 1/2-2x2 1/3)::7/4
tìm số X, biết
a) 1 / 1x2 + 1 / 2x3 + 1 / 3x4 +....+ 1/(X-1) x X
b) 4/3+(X+3)x2-1/2=19/2+4
c) 1+3+5 + .... + 99 / 2+4+...98+X=1
tinh ho to
A=2/1x2+2/2x3+2/3x4+......+2/99x101
B=(1+1/2)x(1+1/3)x(1+1/4)x.......x(1+1/2016)
C=3/1x4+3/4x7+3/7x10+............+3/64x67
D=(1-1/2)x(1-1/3)x(1-1/4)x............x(1-1/20)
Tính hợp lí nếu có thể:
a)3/7+4/9+4/7+5/9
b)1/5+4/10+9/15+16/20+25/25+36/30+49/35+64/40+81/45
c)1/8+1/12+3/8+5/12
d)(1-1/2)x(1-1/3)x(1-1/4)x...x(1-100)
e)9/5:17/15+8/5:17/15
f)2/1x2+2/2x3+2/3x4+...+2/19x20
Ai nhanh nhất mình tick cho
A,(2/1x2+2/2x3+2/3x4+...+2/18x19+2/19x20)-x=2/5
B, (1/21-1/30)x140+1,08:[0,2x(y-1)]=11
C, (x+1)+(x+5)+(x+9)+...+(x+29)=136
D, (y+2)+(y+4)+(y+6)+.....+(y+1996)=998000
Tính hợp lí ( Giúp mk với )
A = (-4/5 + 4/3) + (-5/4 + 14/5) - 7/3
B = 8/3 x 2/5 x 3/8 x 10 x 19/92
C = -5/7 x 2/11 + (-5)/7 x 9/14 + 1/57
D = 12/19 x 7/15 x (-13)/17 x 19/12 x 17/13
E = 1/1x2 + 1/2x3 + 1/3x4 + ....+ 1/49 x 50
1/ So sánh: (a+1) x (a+2) x (a+3)-a* (a+1) x (a+2) và 3 x (a+1) x (a+2)
2/Tính M = 1x2 + 2x3 + 3x4 + ...+2002x2003
(1/1x2+1/2x3+1/3x4.....1/7x8+1/8x9)x100-[5/2-(x+206/100)]:1/2=89
(1-1/2)(1-1/3)(1-1/4)….(1-1/2002).x=1-1/1x2-1/2x3-1/3x4-...1/2002x2003