Ta có : X x 2018 - 2018 = 2018 x 2019 - 4036

=> 2018 x (X - 1) = 2018 x (2019 - 2)

=> 2018 x (X - 1) = 2018 x 2017

Thấy X - 1 = 2017 => x = 2017 + 1 = 2018

Vậy x = ...

X x 2018 - 2018 = 2018 x 2019 - 4036

X x 2018 -2018  =  4070306

X x 2018            = 4070306 + 2018 

X x 2018            = 4072324

X                        = 4072324 : 2018 

X                        = 2018

X x 2018-2018=2018x2019-4036

Xx2028-2018=4070306

Xx2018=4072324

X=2018

k cho mik nha

Ta có : x = 99

=> 100 = x + 1 

Thay vào A ta có : A = x²⁰¹⁸ - 100x²⁰¹⁷ + 100x²⁰¹⁶ - ...... + 100x² - 100x + 2019

=> A = x²⁰¹⁸ - (x + 1)x²⁰¹⁷ + (x + 1)x²⁰¹⁶ - ...... + (x + 1)x² - (x + 1)x + 2019

=> A = x²⁰¹⁸ - x²⁰¹⁸ - x²⁰¹⁷ + x²⁰¹⁷ + x²⁰¹⁶ -.......+ x³ + x² - x² + x + 2019

=> A = x + 2019

=> A = 99 + 2019

=> A = 2118

P/s : ko cần ! :D 

Theo đề bài ra ta có :

x = 99  

Thay vào A ta có :

A = x²⁰¹⁸ - 100x²⁰¹⁷ + 100x²⁰¹⁶ - ... + 100x² - 100x + 2019

\(\Rightarrow\) A = x²⁰¹⁸ - ( x + 1 ) x²⁰¹⁷ + ( x + 1 ) x²⁰¹⁶ - ... + ( x + 1 ) x² - ( x + 1 ) x + 2019

\(\Rightarrow\) A = x²⁰¹⁸ - x²⁰¹⁸ - x²⁰¹⁷ + x²⁰¹⁷ + x²⁰¹⁶- ... + x³ + x² - x² + x + 2019

\(\Rightarrow\) A = x + 2019

\(\Rightarrow\) A = 99 + 2019

\(\Rightarrow\) A = 2118 

\(x\times2019-x=2018\times2018+2018\)

\(x\times\left(2019-1\right)=2018\times\left(2018+1\right)\)

\(x\times2018=2018\times2019\)

\(\Rightarrow x=2019\)

X x 2019 - x =2018 x 2018 + 2018

X x(2019-1) = 2018 x(2018 + 1)

X x 2018 = 2018 x 2019

=> X=2019

Vậy X=2019.

Mơn mấy bn ^^ 

\(\dfrac{2020}{2019}-\dfrac{2019}{2018}+\dfrac{1}{2019}x2018\)
\(=\dfrac{2020}{2019}-\dfrac{2019}{2018}+\dfrac{2018}{2019}=2-\dfrac{2019}{2018}=\dfrac{2017}{2018}\)

\(\frac{x+2019}{x+2018}=\frac{4038}{4037}\)

\(\Rightarrow\left(x+2019\right)4037=\left(x+2018\right)4038\)

\(\Rightarrow4037x+\left(4037\times2019\right)=4038x+\left(4038\times2018\right)\)

\(\Rightarrow4037x+8150703=4038x+8148684\)

\(\Rightarrow4037x-4038x=-8150703+8148684\)

\(\Rightarrow-x=-2019\)

\(\Rightarrow x=2019\)

P/s: Số to kinh -_- Ko chắc đúng đâu.

26 x 84 + 74 x 85

= 26 x 84 + 74 x 84 + 74

= 84 x (26 + 74) + 74

= 84 x 100 + 74

= 840 + 74

= 914

\(\frac{2017\times2018+2019}{2019\times2018-2017}\)

= \(\frac{2019\times2018-2\times2018+2019}{2019\times2018-2017}\)

= \(\frac{2019\times2018-4036+2019}{2019\times2018-2017}\)

= \(\frac{2019\times2018-2017}{2019\times2018-2017}\)

= 1

dung may tinh la duoc roi

Dùng máy tính đó

Hoặc động cái não mà nghĩ đi với

nhân chia trước cộng trừ sau
cứ thế mà tính

nhanh nhanh các bạn ơi

26x84+74x85=8474

2017x2018+2019/2019x2018-2017=4070307

câu trả lời đấy cu

`@` `\text {Ans}`

`\downarrow`

`a)`

`13/50 + 9% + 41/100 + 0,24`

`= 0,26 + 0,09 + 0,41 + 0,24`

`= (0,26 + 0,24) + (0,09 + 0,41)`

`= 0,5 + 0,5`

`= 1`

`b)`

`2018 \times 2020 - 1/2017 + 2018 \times 2019`

`= 2018 \times (2020 + 2019) - 1/2017`

`= 2018 \times 4039 - 1/2017`

`= 8150702`

`c)`

`1/2 + 1/6 + 1/12 + 1/20 +1/30 +1/42`

`=`\(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}\)

`=`\(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{6}-\dfrac{1}{7}\)

`=`\(1-\dfrac{1}{7}\)

`= 6/7`

\(a,\dfrac{13}{50}+9\%+\dfrac{41}{100}+0,24\\ 0,26+0,09+0,41+0,24\\ =\left(0,26+0,24\right)+\left(0,09+0,41\right)\\ =0,5+0,5\\ =1\\ b,2018\times2020-\dfrac{1}{2017}+2018\times2019\\ =2018\times\left(2020+2019\right)-\dfrac{1}{2017}\\ =2018\times4039-\dfrac{1}{2017}\\ =3150702-\dfrac{1}{2017}\\ c,\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}\\ =1-\dfrac{1}{2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}\\ =1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}.........+\dfrac{1}{6}-\dfrac{1}{7}\\ =1-\dfrac{1}{7}\\ =\dfrac{6}{7}\)

Cảm ơn các bạn đã trả lời giúp mình câu hỏi nha