a,

104,4 . x -14,1 . x + 9,6 . x =25 

x(104,4 - 14,1 + 9,6 ) = 25

x.99,9 = 25

x = \(\frac{250}{999}\)

b)

\(\frac{2009.2010+2000}{2011.2010-2020}=\frac{2009.2010+2000}{\left(2009+2\right).2010-2020}\)

                                    \(=\frac{2009.2010+2000}{2009.2010+2.2010-2020}\)

                                    \(=\frac{2009.2010+2000}{2009.2010+4020-2020}\)

                                    \(=\frac{2009.2010+2000}{2009.2010+2000}\)         

                                     \(=1\)

Thanh you 

\(\dfrac{25}{27};\dfrac{51}{53};\dfrac{47}{49};\dfrac{103}{105};\dfrac{2009}{2011};\dfrac{1963}{1963};\)

25/27,47/49,51/53,103/105,2009/2011,1963/1963.

\(=\dfrac{2019.2010+1,005.2010}{2011.2010+2.2010}=\dfrac{2010\left(2019+1,005\right)}{2010\cdot\left(2011+2\right)}\)

\(=\dfrac{2020,005}{2013}=\dfrac{2020005}{2013000}=\dfrac{404001}{402600}\)

\(A=\frac{2013\cdot2012-2009}{2012\cdot2011+2015}\)

\(A=\frac{2012\cdot2011+4024-2009}{2012\cdot2011+2015}\)

\(A=\frac{2012\cdot2011+2015}{2021\cdot2011+2015}\)

\(A=1\)

Bài giải rất đúng,hữu dụng

thục sự mình cũng cần trả lời câu này kết quả bằng 1 nhưng ko biết cách giải

=(1-2-3+4)+(5-6-7+8)+...+(2005-2006-2007+2008)+2009

=2009

\(\frac{2x-4,36}{0,125}=0,25.42,9-11,7.0,25+0,25.0,8\)

\(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.\left(42,9-11.7+0,8\right)\)

\(\Leftrightarrow\frac{2x-4,36}{0,125}=0,25.32\)

\(\Leftrightarrow\frac{2x-4,36}{0,125}=8\)

\(\Leftrightarrow2x-4,36=1\)

\(\Leftrightarrow2x=5,36\)

\(\Leftrightarrow x=2,68\)

b) \(N=\frac{1}{1.5}+\frac{1}{5.10}+\frac{1}{10.15}+\frac{1}{15.20}+...+\frac{1}{2005.2010}\)

\(\Leftrightarrow N=\frac{1}{5}\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+\frac{1}{15}-\frac{1}{20}+...+\frac{1}{2005}-\frac{1}{2010}\right)\)

\(\Leftrightarrow N=\frac{1}{5}\left(1-\frac{1}{2010}\right)\)

\(\Leftrightarrow N=\frac{1}{5}.\frac{2009}{2010}=\frac{2009}{10050}\)

Bài 1:

a)\(\frac{2\cdot x-4,36}{0,125}=0,25\cdot42,9-11,7\cdot0,25+0,25\cdot0,8\)

\(\frac{2\cdot x-4,36}{0,125}=0,25\cdot\left(42,9-11,7+0,8\right)\)

\(\frac{2\cdot x-4,36}{0,125}=0,25\cdot32\)

\(\frac{2\cdot x-4,36}{0,125}=8\)

\(2\cdot x-4,36=8\cdot0,125\)

\(2\cdot x-4,36=1\)

\(2\cdot x=1+4,36\)

\(2\cdot x=5,36\)

\(x=\frac{5,36}{2}=2,68\)

b) \(N=\frac{1}{1\cdot5}+\frac{1}{5\cdot10}+\frac{1}{10\cdot15}+\frac{1}{15\cdot20}+...+\frac{1}{2005\cdot2010}\)

\(4N=\frac{4}{1\cdot5}+\frac{4}{5\cdot10}+\frac{4}{10\cdot15}+\frac{4}{15\cdot20}+...+\frac{4}{2005\cdot2010}\)

\(4N=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+\frac{1}{15}-\frac{1}{20}+...+\frac{1}{2005}-\frac{1}{2010}\)

\(4N=1-\frac{1}{2010}=\frac{2009}{2010}\)

\(N=\frac{2009}{2010}\div4=\frac{2009}{8040}\)

Bài 2:

a) ( x + 5,2 ) : 3,2 = 4,7 ( dư 0,5 )

\(x+5,2=4,7\cdot3,2+0,5\)

\(x+5,2=15,54\)

\(x=15,54-5,2=10,34\)

b)\(A=\frac{4047991-2010\cdot2009}{4050000-2011\cdot2009}\)

\(A=\frac{4047991-2010\cdot2009}{4050000-2009-2010\cdot2009}\)

\(A=\frac{4047991-2010\cdot2009}{4047991-2010\cdot2009}=1\)

Bài 3:

a) \(104,5\cdot x-14,1\cdot x+9,6\cdot x=25\)

\(x\cdot\left(104,5-14,1+9,6\right)=25\)

\(x\cdot100=25\)

\(x=\frac{25}{100}=\frac{1}{4}=0,25\)

b) \(T=\frac{2009\cdot2010+2000}{2011\cdot2010-2020}\)

\(T=\frac{2009\cdot2010+2000}{2009\cdot2010+4020-2020}\)

\(T=\frac{2009\cdot2010+2000}{2009\cdot2010+2000}=1\)

39900

201100

k nha!

= 399 x (105 - 5)

= 399 x 100

= 39900

= 2011 x (75 + 25)

= 2011 x 100

= 201100