\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+.....+\frac{1}{x\left(x+1\right)}=\frac{99}{100}\)
\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+.....+\frac{1}{x}-\frac{1}{x+1}=\frac{99}{100}\)
\(1-\frac{1}{x+1}=\frac{99}{100}\)
=> \(\frac{1}{x+1}=1-\frac{99}{100}=\frac{1}{100}\)
=> x+1 = 100
=> x = 100 - 1
=> x = 99
1/1x2 + 1/2x3 + 1/3x4 + ... 1/99 x 100
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
(1/1x2+1/2x3+1/3x4.....1/7x8+1/8x9)x100-[5/2-(x+206/100)]:1/2=89
1) Tính nhanh
a) 12,5 x 32 x 8
b) 20,9 + 20,9 x 99
c) 1/1x2 + 1/2x3 + 1/3x4 +.......1/49x50
2) Tìm y biết
a) 45 - 5 x (y + 1) = 10
b) y : 2 + y : 2 = 15
x/1x2 +x/2x3 + x/3x4+ .....+x/2017x2018=-1
bài 1 tính
a, 24 x 66 - 24 + 36 x 24
b, 29 x 173 - 29 x 72 -29
c, 1+5+10+15+...+55+60
d, 1x2+2x3+3x4 +...+18x19+19x20
bài 2 tìm x
a,106- ( x+ 7) =9
b, 2 x ( x+ 4) + 5 =65
c, (16x x -32) x 45=0
d, x+4 x x = 100 : 5
A = 1x2 +2x3+3x4+........+99 x 100
B = 1x2x3 + 2x3x4 + 4x5x6 +...........+ 98 x99 x 100
tính A,B
1313/1212 : x = 1/1x2+1/2x3+1/3x4+1/4x5+1/5
(1-1/2)(1-1/3)(1-1/4)….(1-1/2002).x=1-1/1x2-1/2x3-1/3x4-...1/2002x2003
