( m - 1 )² - m² = 0
<=> ( m - 1 - m ) ( m - 1 + m ) = 0
<=> \(\left[ \begin{array}{l}m-1-m=0\\m-1+m=0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}-1=0 ( vl )\\2m-1 = 0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}loại\\2m=1 \end{array} \right.\)
<=>\(\left[ \begin{array}{l}loại\\m=\frac{1}{2}\end{array} \right.\)
Vậy m = $\frac{1}{2}$ .
