Question

x1, x2, x3 là nghiệm phương trình x³-x-1=0. Tính giá trị biểu thức    T= \(\frac{1+x1}{1-x1}\)\(+\frac{1+x2}{1-x2}\)\(+\frac{1+x3}{1-x3}\)

Mấy bạn giúp mik với

Answer 1

\(\frac{x+4}{2000}+\frac{x+3}{2001}=\frac{x+2}{2002}+\frac{x+1}{2003}\)

\(\Leftrightarrow2+\frac{x+4}{2000}+\frac{x+3}{2001}=2+\frac{x+2}{2002}+\frac{x+1}{2003}\)

\(\Leftrightarrow\left(\frac{x+4}{2000}+1\right)+\left(\frac{x+3}{2001}+1\right)=\left(\frac{x+2}{2002}+1\right)+\left(\frac{x+1}{2001}+1\right)\)

\(\Leftrightarrow\frac{x+2004}{2000}+\frac{x+2004}{2001}=\frac{x+2004}{2002}+\frac{x+2004}{2003}\)

\(\Leftrightarrow\left(x+2004\right)\left(\frac{1}{2000}+\frac{1}{2001}-\frac{1}{2002}-\frac{1}{2003}\right)=0\)

Mà \(\frac{1}{2000}+\frac{1}{2001}-\frac{1}{2002}-\frac{1}{2003}\ne0\)

Suy ra x+2004=0

\(\Leftrightarrow x=-2004\)