Toán Lớp 8: Giải phương trình |2x – 5| + |2×2 – 7x + 5| = 0
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Toán Lớp 8: Giải phương trình |2x – 5| + |2×2 – 7x + 5| = 0
Comments ( 2 )
\left[ \begin{array}{l}
|2x – 5| \ge 0\\
\mid 2{x^2} – 7x + 5\mid \ge 0
\end{array} \right. \Rightarrow \left| {2x – 5} \right| + \left| {2{x^2} – 7x + 5} \right| \ge 0\\
dau\,\, = \,\,xay\,\,ra\,\,khi:\\
\left[ \begin{array}{l}
2x – 5 = 0\\
2{x^2} – 7x + 5 = 0
\end{array} \right. \Rightarrow \left[ \begin{array}{l}
x = \frac{5}{2}\\
x = 1
\end{array} \right. \Rightarrow x = \frac{5}{2}
\end{array}\]