\(a,\left(1-\dfrac{1}{10}\right)\times\left(1-\dfrac{1}{11}\right)\times\left(1-\dfrac{1}{12}\right)\times\left(1-\dfrac{1}{13}\right)\times\left(1-\dfrac{1}{14}\right)\times\left(1-\dfrac{1}{15}\right)=\dfrac{9}{10}\times\dfrac{10}{11}\times\dfrac{11}{12}\times\dfrac{12}{13}\times\dfrac{13}{14}\times\dfrac{14}{15}=\dfrac{9}{15}=\dfrac{3}{5}\)

\(b,\dfrac{2013\times2012-2}{2011+2011\times2013}=\dfrac{\left(2014-1\right)\times2012-2}{2011\times\left(2013+1\right)}=\dfrac{2014\times2012-2012-2}{2011\times2014}=\dfrac{2014\times2012-2014}{2011\times2014}=\dfrac{2014\times\left(2012-1\right)}{2011\times2014}=\dfrac{2011\times2014}{2011\times2014}=1\)

3/5,1

$\frac{\frac{2010}{2011}}{\frac{2012}{2013}}+\frac{\frac{2011}{2012}}{\frac{2013}{2014}}+\frac{\frac{2012}{2013}}{\frac{2014}{2015}}$

$\frac{\frac{2010}{2011}}{\frac{2012}{2013}}+\frac{\frac{2011}{2012}}{\frac{2013}{2014}}+\frac{\frac{2012}{2013}}{\frac{2014}{2015}}$

$\frac{\frac{2010+2011+2012}{2011+2012+2013}}{\frac{2012+2013+2014}{2013+2014+2015}}$

$\frac{\frac{2010}{2011}+\frac{2011}{2012}+\frac{2012}{2013}}{\frac{2012+2013+2014}{2013+2014+2015}}$

$\frac{\frac{2010+2011+2012}{2011+2012+2013}}{\frac{2012}{2013}+\frac{2013}{2014}+\frac{2014}{2015}}$

dễ ợt nhưng éo biết làm thông cảm nha

ban Dang Ha Trang an noi gi ki vay 

\(\frac{2011\times2012+2013\times21+1991}{2012\times2013-2012\times2012}\)

\(=\frac{2011\times2012+2013\times\left(21+1991\right)}{2012\times2013-2012\times2012}\)

\(=\frac{2011\times2012+2013\times2012}{2012\times2013-2012\times2012}=\frac{2011}{2012}\)

\(2012M=\frac{2012^{2013}}{2013^{2013}}\) 

\(2012M=\frac{2012^{2013}}{2013^{2013}}=\frac{2012}{2013}\) 

=>\(M=\frac{2012}{2013}:2012=\frac{1}{2013}\) 

\(2012N=\frac{2012\left(2012^{2012}+2012\right)}{2013^{2013}+2013}=\frac{2012^{2013}+2012^2}{2013^{2013}+2013}\) 

=>\(N=\frac{2012+2012^2}{2013+2013}:2012=\frac{4050156}{4026}:2012=\frac{1}{2}\) 

=>\(\frac{1}{2013}< \frac{1}{2}\) (vì phân số nào có mẫu bé hơn thì phân số đó lớn hơn)

=> M < N

Cho A=$\frac{n-2}{n+3}$n−2n+‍3 .Tìm giá trị của n để

a) A là phân số

b) A là một số nguyên

mọi người giải hộ tui với!!!

A=\(\frac{n-2}{n+3}\)

\(A=\frac{n-2}{n+3}=\frac{n+3-5}{n+3}=1+\frac{5}{n+3}\)

a) \(n\in R\)  trừ   \(n=-3\)

b) để A là số nguyên thì \(\frac{5}{n+3}\in Z\) 

Suy ra \(n+3\in\left\{1;5;-1;-5\right\}\)

Suy ra \(n\in\left\{-2;2;-4;-8\right\}\)

 = 2012 x (1001-1) + 2013 x (999+1)

 = 2012 x 1000 + 2013 x 1000

 = 1000 x (2012+2013)

 = 1000 x 4025 = 4025000

k mk nha

 = 2012 x (1001-1) + 2013 x (999+1)

 = 2012 x 1000 + 2013 x 1000

 = 1000 x (2012+2013)

 = 1000 x 4025 = 4025000

2012 x (1001-1)+2013 x (999+1)

=2012 x 1000 + 2013 x 1000

=1000 x (2012 + 2013)

=1000 x 4025=4025000

k cho chị nha cưng!

2012 x 2013 - 1013 x 2013 + 2013

= 2012 x 2013 - 1013 x 2013 + 2013 x 1

= 2013 x ( 2012 - 1013 + 1 )

= 2013 x         1000

=       2013000

a) 2012x2013-1013x2013+2013

=2013(2012-1013+1)

=2013x1000

=2013000

\(2012x2013-1013x2013+2013\)

\(=2013x\left(2012-1013+1\right)\)

\(=2013x1000\)

\(=2013000\)

Nhớ ấn đúng cho mình nha!