tính nhanh 2011 : 25 - 2009 : 25
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
b)(1-3-5+7)+(9-11-13+15)+...+(2009-2011-2013+2015)
=0+0+...+0
=0
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)
\(\frac{2009.2010+2000}{2011.2010-2020}=\frac{2009.2010+2000}{\left(2009+2\right).2010-2020}\)
\(=\frac{2009.2010+2000}{2009.2010+2.2010-2020}\)
\(=\frac{2009.2010+2000}{2009.2010+4020-2020}\)
\(=\frac{2009.2010+2000}{2009.2010+2000}\)
\(=1\)
\(\text{Ta có : }\)\(\frac{25}{4.9}+\frac{25}{9.14}+\frac{25}{14.19}+......+\frac{25}{2004.2009}\)
\(=5.\left(\frac{5}{4.9}+\frac{5}{9.14}+\frac{5}{14.19}+......+\frac{5}{2004.2009}\right)\)
\(=5\left(\frac{1}{4}-\frac{1}{9}+\frac{1}{9}-\frac{1}{14}+......+\frac{1}{2004}-\frac{1}{2009}\right)\)
\(=5\left(\frac{1}{4}-\frac{1}{2009}\right)\)
\(=5.\frac{2005}{8036}=\frac{10025}{8036}\)
( - 2009 - 2009 - 2009 - 2009 ) . ( - 25 )
= 2009 + 2009 + 2009 + 2009 . ( - 25 )
= 2009 . 4 . ( - 25 )
= 2009 . [ 4 . ( - 25 ) ]
= 2009 . ( - 100 )
= - 200 900
\(A=\frac{4047991-2010.2009}{4050000-2011.2009}\)
\(\Rightarrow A=\frac{404791-2010.2009}{4047911+2009-2011.2009}\)
\(\Rightarrow A=\frac{4047911-2010.2009}{4047911-2010.2009}\)
\(\Rightarrow A=1\)
Vậy A = 1
~Study well~
#๖ۣۜNamiko#
\(\dfrac{25}{27};\dfrac{51}{53};\dfrac{47}{49};\dfrac{103}{105};\dfrac{2009}{2011};\dfrac{1963}{1963};\)
2011 × 2010 - 1 / 2009 × 2011 + 2010
=2011 × 2009 + 2011 - 1 / 2009 × 2011 + 2010
= 2011 × 2009 + (2011 - 1) / 2009 × 2011 + 2010
= 2011 × 2009 + 2010 / 2009 × 2011 + 2010
= 1
2011 : 25 - 2009 : 25
= ( 2011 - 2009 ) : 25
= 2 : 25
= 0,08
Mk nhanh nhất đó
2011:25-2009:25
=(2011-2009):25
=2:25
=0.08
tk va ket ban nha