`@Fù`

`=1/(1×2)+1/(2×3)+1/(3×4)+...+1/(72×73)`

`=1/1-1/2+1/2-1/3+...+1/72-1/73`

`=1-1/73`

`=72/73`

tích đúng mình giải cho

= 1/1x2 + 1/2x3 + 1/3x4 + 1/4x5 + 1/5 x 6

= (1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + (1/4 - 1/5) + (1/5 - 1/6)

= 1 - 1/6

= 5/6

nha,mơn nhìu

\(\frac{1}{1}x\frac{1}{2}+\frac{1}{2}x\frac{1}{3}+\frac{1}{3}x\frac{1}{4}+\frac{1}{4}x\frac{1}{5}+\frac{1}{5}x\frac{1}{6}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\)

\(=1-\frac{1}{6}=\frac{5}{6}\)

a: \(=60\cdot\dfrac{17}{20}=51\)

b: \(=\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot\dfrac{3}{4}\cdot\dfrac{4}{5}=\dfrac{1}{5}\)

Lớp 8 đâu?

lp 6 đâu

lớp 6 đâu

\(\left(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{9\cdot10}\right)\cdot100-\left[\frac{5}{2}:\left(x+\frac{206}{100}\right)\right]:\frac{1}{2}=89\)

\(\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\right)\cdot100-\left[\frac{5}{2}:\left(x+\frac{103}{50}\right)\right]\cdot2=89\)

\(\left(1-\frac{1}{10}\right)\cdot100-\frac{5}{2}:\left(x+\frac{103}{50}\right)\cdot2=89\)

\(\frac{9}{10}\cdot100-\frac{5}{2}\cdot2:\left(x+\frac{103}{50}\right)=89\)

\(90-5\cdot\left(x+\frac{103}{50}\right)=89\)

\(5\cdot\left(x+\frac{103}{50}\right)=1\)

\(x+\frac{103}{50}=\frac{1}{5}\)

\(x=-\frac{93}{50}\)

1 + 2 = 3

1 + 3 = 4

1+ 4 = 5

1 + 5 = 6 

1x1 tỷ = 1 tỷ

= 3 

= 4

= 5

= 6

= 1 tỉ

3

4

5

6

1 tỉ

k mk

1 + 1 + 1+ 1 - 1 + 1 +1 - 1 x 1 + 1 - 1 + 1 + 2 = 7

1+1+1+1-1+1+1-1x1+1-1+1+2=?

=7

hok tốt !

1 + 1 + 1 + 1 - 1 + 1 + 1 - 1 * 1  + 1 - 1 + 1 + 2

=  4 - 1 + 1 + 1 - 1 + 1 - 1 + 1 + 2

= 3 + 1 + 1 - 1 + 1 - 1 + 1 + 2

= 4 + 1 - 1 + 1 - 1 + 1 + 2

= 5 - 1 + 1 - 1 + 1 +2

= 4 + 1 - 1 + 1 + 2

= 5 - 1 + 1 +2

= 4 + 1 + 2

=7

\(\left(1+\frac{1}{2}\right)\cdot\left(1+\frac{1}{3}\right)\cdot...\cdot\left(1+\frac{1}{2010}\right)\)

\(=\frac{3}{2}\cdot\frac{4}{3}\cdot\frac{5}{4}\cdot...\cdot\frac{2011}{2010}\)

\(=\frac{2011}{2}\)

\(=1005,5\)