1/10x(2/9x9/2)x(3/8x8/3)x(5/6x6/5)=1/10x1x1x1=1/10

\(=\frac{1}{5}\times\frac{1}{3}\times\frac{3}{7}\times\frac{1}{2}\)

\(=\left(\frac{1}{5}\times\frac{1}{2}\right)\times\left(\frac{1}{3}\times\frac{3}{7}\right)\)

\(=\frac{1}{10}\times\frac{1}{7}\)

\(=\frac{1}{70}\)

\(\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\times\left(1-\frac{1}{5}\right)...\times\left(1-\frac{1}{100}\right)\)

=\(\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\times...\times\frac{99}{100}\)

=\(\frac{1\times2\times3\times4\times...\times99}{2\times3\times4\times5\times...\times100}\)

= \(\frac{1}{100}\)

194/175

co ai giai giup  minh voi please!

ban oi cu the

\(\left[12\cdot15-x\right]\cdot\frac{1}{4}=120\cdot\frac{1}{4}\)

\(\Leftrightarrow\left[180-x\right]\cdot\frac{1}{4}=30\)

\(\Leftrightarrow180-x=30:\frac{1}{4}\)

\(\Leftrightarrow180-x=120\)

\(\Leftrightarrow x=60\)

tl moi cau

\(\left[x\cdot0,25+2012\right]\cdot2013=\left[50+2012\right]\cdot2013\)

\(\Leftrightarrow x\cdot0,25\cdot2013+2012\cdot2013=2062\cdot2013\)

\(\Leftrightarrow x\cdot\frac{2013}{4}+4050156=4150806\)

\(\Leftrightarrow x\cdot\frac{2013}{4}=100650\)

\(\Leftrightarrow x=100650:\frac{2013}{4}=100650\cdot\frac{4}{2013}=200\)

=1125

bang mot ngan mot tram hai muoi lam

  125 x 3 + 125 x 2 + 125 x 3 + 125 x 1

= 125 x ( 3 + 2 + 3 + 1 )

= 125 x ( 5 + 3 + 1 )

= 125 x ( 8 + 1 )

= 125 x 9 

 = 1125

\(\frac{2015\cdot2017-1}{2014+2015\cdot2016}\)\(\cdot\frac{2}{3}\)

\(=\frac{2015\cdot\left(2016+1\right)-1}{2014+2015\cdot2016}\cdot\frac{2}{3}\)

\(=\frac{2015\cdot2016+\left(2015-1\right)}{2014+2015\cdot2016}\cdot\frac{2}{3}\)

\(=\frac{2015\cdot2016+2014}{2014+2015\cdot2016}\cdot\frac{2}{3}\)

\(=1\cdot\frac{2}{3}\)

\(=\frac{2}{3}\)

=6772415

6772415 nha!

Mình tính bằng máy tính CASIO đấy nhé.Đúng 10000000000000000000000000000000000000000000000000000000000000000000.....%

Bạn dùng công thức này mà làm nhé :\(\frac{n}{a\times\left(a+n\right)}=\frac{1}{a}-\frac{1}{a+n}\)

Ví dụ :\(\frac{2}{3\times5}=\frac{1}{3}-\frac{1}{5};\frac{3}{4\times7}=\frac{1}{4}-\frac{1}{7};\frac{5}{6\times11}=\frac{1}{6}-\frac{1}{11}\)

minh ra 2 nhung chac khong dung