Tính nhanh.\(\frac{5}{1.4}+\frac{5}{4.7}+...+\frac{5}{57.40}\)

\(=5.\frac{1}{3}\left(\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{4}{37.40}\right)\)

\(=\frac{5}{3}\left(\frac{1}{1}-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{37}-\frac{1}{40}\right)\)

\(=\frac{5}{3}\left(\frac{1}{1}-\frac{1}{40}\right)\)

\(=\frac{5}{3}.\frac{39}{40}\)

\(=\frac{13}{8}\)

Rút gobj p/s

\(\frac{2019.2020+4038}{2022.2011-4044}\)

\(=\frac{2019.\left(2020+2\right)}{2020.\left(2011-2\right)}\)

\(=\frac{2019.2022}{2022.2019}\)

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

Study well 

Cho mk sorry nha dong thứ 2 từ trên cuống dưới phải là 

\(5.\frac{1}{3}\left(\frac{3}{1.4}+\frac{3}{4.7}+...+\frac{3}{37.40}\right)\) nha 

Sorry nhiều 

Study well 

:))

hi cậu nha )

Bài này dễ mà!

\(P\left(2019\right)=2019^3\left(a+2016\right)+2019\left(b+2017\right)+2018=2020\)

                                       \(\Rightarrow2019^3\left(a+2016\right)+2019\left(b+2017\right)=2\)

Có: \(P\left(-2019\right)=-2019^3\left(a+2016\right)-2019\left(b+2017\right)+2018\)

                               \(=-\left[2019^3\left(a+2016\right)+2019\left(b+2017\right)\right]+2018\)

                               \(=-2+2018=2016\)

jerlegtret6t54654t6456

ta có :\(E=\frac{2019^{2019}+1}{2019^{2020}+1}\Leftrightarrow2019\cdot E=\frac{2019^{2020}+2019}{2019^{2020}+1}=1+\frac{2019}{2019^{2020}+1}\)

\(F=\frac{2019^{2020}+1}{2019^{2021}+1}\Leftrightarrow2019\cdot F=\frac{2019^{2021}+2019}{2019^{2021}+1}=1+\frac{2019}{2019^{2021}+1}\)

vì \(\frac{2019}{2019^{2020}+1}>\frac{2019}{2019^{2021}+1}\) nên E>F

E=2019 x 2019 x 2019 x ........ x 2019 x2019 +1 /2019 x 2019 x 2019 x.........x 2019 x 2019 + 1

E=1+1/2019+1

E=2/2020

E=1/1010

F=2019 x 2019 x 2019 x .......... x 2019 x 2019 +1 / 2019 x 2019 x 2019 x ....... x 2019 x 2019 +1

F= 1+1/2019+1

F=2/2020

F=1/1010

từ đó ta có E=F(=1/1010)

Ta có

 1 x 2 x 3 x .... x 2019 x 2020 chữ số tận cùng là 0

1 x 3 x 5 x ... x 2017 x 2019 chữ số tận cùng là 5

  Vậy A = 1 x 2 x 3 x .... x 2019 x 2020 - 1 x 3 x 5 x .... x 2017 x 2019 chữ số tận cùng sẽ là 5

chữ số tận cùng sẽ là 5

a)\(M=\frac{2019\times2020-2}{2018+2018\times2020}=\frac{2019\times2020-2}{2018+2018\times2020+2020-2020}=\frac{2019\times2020-2}{\left(2018+1\right)\times2020+2018-2020}=\frac{2019\times2020-2}{2019\times2020-2}=1\\ N=\frac{-2019\times20202020}{20192019\times2020}=\frac{-2019\times10001\times2020}{2019\times10001\times2020}=-1\)

b)\(5\left|x-1\right|=3M-2N=5\\ \left|x-1\right|=1\Rightarrow\hept{\begin{cases}x-1=1\Rightarrow x=2\\x-1=-1\Rightarrow x=0\end{cases}}\)

54 x 5 + 54 x 2 +54 x ...=594 đố các bạn điền số mấy vào ô trống

\(4x2020x25-5x2029x20\)

\(=2020x25x4-5x20x2029\)

\(=2020x100-100x2029=100x\left(2020-2019\right)=100.1=100\)