Tìm x
a)\(\frac{x-5}{2000}\)+ \(\frac{x-4}{1999}\)+ \(\frac{x-3}{1998}\)= \(\frac{x-2}{1997}\)+ \(\frac{x-1}{1996}+\frac{x}{1995}\)
b) \(\frac{x+4}{2015}+\frac{x+5}{2016}=\frac{x+6}{2017}+\frac{x+7}{2018}\)
Tìm x, y, thuộc Z
\(\frac{x}{4}-\frac{1}{y}=\frac{1}{2}\)
Tìm x,y,z thuộc Q
x.(x+y+z) = -5
y.(x+y+z) = 9
z.(x+y+z) = 5
Tính hợp lí
A= \(\frac{1}{15}+\frac{1}{^{15^2}}+\frac{1}{15^3}+...+\frac{1}{15^{2017}}\)
B= \(1.2+2.3+3.4+4.5+...+2016.2017\)
a. \(\frac{x-5}{2000}+\frac{x-4}{1999}+\frac{x-3}{1998}=\frac{x-2}{1997}+\frac{x-1}{1996}+\frac{x}{1995}\)
\(\Leftrightarrow\left(\frac{x-5}{2000}+1\right)+\left(\frac{x-4}{1999}+1\right)+\left(\frac{x-3}{1998}+1\right)=\left(\frac{x-2}{1997}+1\right)+\left(\frac{x-1}{1996}+1\right)+\left(\frac{x}{1995}+1\right)\)
\(\Leftrightarrow\left(x+1995\right)\left(\frac{1}{2000}+\frac{1}{1999}+\frac{1}{1998}-\frac{1}{1997}-\frac{1}{1996}-\frac{1}{1995}\right)=0\)
\(\Leftrightarrow x+1995=0\)
\(\Leftrightarrow x=-1995\)
