Số lượng thừa số:
`(2019-2):1+1=2018` là số chẵn
`=>(1/2-1)*(1/3-1)*...*(1/2019-1)`
`=(1-1/2)(1-1/3)*...*(1-1/2019)`
`=1/2*2/3*...*2018/2019`
`=1/2019`
\(\dfrac{x+1}{2019}+\dfrac{x+2}{2018}=\dfrac{x+3}{2017}+\dfrac{x+4}{2016}\)
Bài 1: Tính giá trị của biểu thức sau
A=1-\(\dfrac{50-\dfrac{4}{2018}+\dfrac{2}{2019}-\dfrac{2}{2020}}{100-\dfrac{8}{2018} +\dfrac{4}{2019}-\dfrac{4}{2020}}\)
B=\(\dfrac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.14^3}\)
C=\(x^{2020}\)-\(y^{2020}\)+\(xy^{2019}\)-\(x^{2019}\).y+2019 biết x-y=0
Mong mn giúp đỡ
A=1-\(\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{2017}-\dfrac{1}{2018}+\dfrac{1}{2019}\)
B=\(\dfrac{1}{1010}+\dfrac{1}{1011}+\dfrac{1}{1012}+...+\dfrac{1}{2019}\)
Tính \(^{\left(A-B\right)^{2019}}\)
a, \(\left(2x-1\right)\left(x+\dfrac{2}{3}\right)=0\)
b, \(\dfrac{x+4}{2019}+\dfrac{x+3}{2020}=\dfrac{x+2}{2021}+\dfrac{x+1}{2022}\)
1/ 3 x (x - \(\dfrac{1}{2}\)) - 3 x (x - \(\dfrac{1}{3}\)) - (x - \(\dfrac{1}{2}\)) = 0
2/ \(\dfrac{-2x+1}{3}\) + \(\dfrac{1}{2}\) = \(\dfrac{-1}{3}\)
Tìm x, biết
a)\(\dfrac{1}{2}\)x\(x\)-\(\dfrac{7}{3}\)=\(\dfrac{-5}{6}\)+\(\dfrac{3}{4}\)x\(x\)
b)\(\dfrac{4}{5}\)x\(x\)-\(\dfrac{6}{5}\)=\(\dfrac{1}{2}\)+\(\dfrac{3}{2}\)x\(x\)
c)\(\dfrac{2}{5}\)x(3x\(x\)+\(\dfrac{3}{4}\))=\(1\dfrac{1}{5}\)-\(\dfrac{1}{3}\)x\(x\)
d)2x(3x\(x \)+\(\dfrac{3}{4}\))+\(\dfrac{4}{5}\)=\(\dfrac{1}{2}\)-2x\(x\)
\(\dfrac{x-3}{3}=\dfrac{2x+1}{5}\)
\(\dfrac{x+1}{22}=\dfrac{6}{x}\)
\(\dfrac{2x-1}{2}=\dfrac{5}{x}\)
\(\dfrac{2x-1}{21}=\dfrac{3}{2x+1}\)
\(\dfrac{2x+1}{9}=\dfrac{5}{x+1}\)
Tìm x
1.tính \(\dfrac{1}{99.97}-\dfrac{1}{97.95}-\dfrac{1}{95.93}-...-\dfrac{1}{5.3}-\dfrac{1}{3.1}\)
2. tìm x. biết : \(|x+\dfrac{1}{2}|+|x+\dfrac{1}{6}|+|x+\dfrac{1}{12}|+|x+\dfrac{1}{20}|+...+|x+\dfrac{1}{110}|=11x\)
3. tính gtri b thức C= \(2x^5-5y^3+2015\) tại x, y thỏa mãn: \(|x-1|+\left(y+2\right)^{20}=0\)
\(\left(\dfrac{-2}{3}\right)^2.x=\left(\dfrac{-2}{3}\right)^5\)
\(\left(x-\dfrac{1}{2}\right)^3=\dfrac{1}{27}\)
\(\left(\dfrac{2}{3}x-1\right)\left(\dfrac{3}{4}x+\dfrac{1}{2}\right)=0\)
\(\dfrac{4}{9}:x=3\dfrac{1}{3}:2,25\)
\(1\dfrac{1}{3}:0,8=\dfrac{2}{3}:0,1x\)
Tìm \(\left(x\right)\):
a) \(\left(x-\dfrac{1}{2}\right)^2\):\(\dfrac{2}{9}\) =\(\left(-1\dfrac{1}{3}\right)\):\(\left(\dfrac{1}{2}-x\right)\)
b) \(\dfrac{3.x-1}{4}\)=\(\dfrac{2.x-5}{3}\)
c) \(\dfrac{3}{-2}\)=\(\dfrac{x-3}{3.x+1}\)
Cú tui mấy ông bà ơi:)) Làm dc thì làm giúp tui nhen, cảm ơn nè
