= ( 1 + 3 + 5 + ... + 2011 ) - ( 2 + 6 + 8 + ... + 2010 )

= [ 1006 x ( 2011 + 1 ) : 2 ] - [ 1005 x ( 2010 + 2 ) : 2 ]

= ( 1006 x 2012 : 2 ) - ( 1005 x 2012 : 2 )

= ( 2024072 : 2 ) - ( 2022060 : 2 )

= 1012036 - 1011030

= 1006

m giong ban kia !ban nao tk mk di !

2017*4+2017*62+2017*35-2017

=2017*(4+62+35-1)

=2017*100

=201700

2006*42+2006*39+2006*21-2006*2

=2006*(42+39+21-2)

=2006*100

=200600

 k mik đi

A , 201700

B, 200600

=\(\frac{2}{5}+1\)

=\(\frac{7}{5}\)

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

\(=\frac{2}{5}+\left(\frac{3}{4}+\frac{1}{4}\right)\)

\(=\frac{2}{5}+1\)

\(=\frac{2}{5}+\frac{5}{5}\)

\(=\frac{7}{5}\)

y=\(\frac{2006x2005-1}{2004x2006+2005}=\frac{2006x2005-1}{\left(2005-1\right)x2006+2005}=\frac{2006x2005-1}{2005x2006-2006+2005}=\frac{2006x2005-1}{2005x2006-1}=1\)

\(\frac{27}{8}-\frac{7}{3}+\frac{4}{3}-2\)

=\(\frac{27}{8}-\left(\frac{7}{3}-\frac{4}{4}\right)-2\)

=\(\frac{27}{8}-1-2\)

=\(\frac{27}{8}-\frac{8}{8}-\frac{16}{8}\)

=\(\frac{3}{8}\)

sai hết

mấy bn giúp mik với

\(\frac{11}{2}\): \(\frac{11}{3}\): \(\frac{11}{4}\)

= \(\frac{11}{2}\): ( \(\frac{3}{11}\): \(\frac{4}{11}\)

Tìm tổng các chữ số :

( 50 - 1 ) : 1 +1 = .... 

Tổng dãy số là; 

( 1 +49 ) . ( kq của phép tính đầu )  -1 : 2 + 50 = ....

\(\frac{3}{1\times2}+\frac{3}{2\times3}+...+\frac{3}{5\times6}\)

\(=3\left(\frac{1}{1\times2}+\frac{1}{2\times3}+...+\frac{1}{5\times6}\right)\)

\(=3\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{5}-\frac{1}{6}\right)\)

\(=3\left(1-\frac{1}{6}\right)=3\times\frac{5}{6}=\frac{5}{2}\)

=> S=3(1/1*2+1/2*3+...........+1/5*6

=>S=3*(1-1/6)

=>S=3*5/6

=>S=5/2

 đúng 100%