Đáp án:
( 5 - 2$x_{}$ )² - 16 = 16
⇔ ( 5 - 2$x_{}$ )² - 16 - 16 = 0
⇔ ( 5 - 2$x_{}$ )² - 32 = 0
⇔ ( 5 - 2$x_{}$ )² - ( 4√2 )² = 0
⇔ ( 5 - 2$x_{}$ + 4√2 ) × ( 5 - 2$x_{}$ - 4√2 ) = 0
⇔\(\left[ \begin{array}{l}5 - 2x + 4√2 = 0\\5 - 2x - 4√2 = 0\end{array} \right.\)
⇔\(\left[ \begin{array}{l} - 2x + 4√2 = -5\\ - 2x - 4√2 = -5\end{array} \right.\)
⇔\(\left[ \begin{array}{l} - 2x = -5 - 4√2 \\ - 2x = -5 + 4√2\end{array} \right.\)
⇔\(\left[ \begin{array}{l} x = \frac{- 5 - 4√2}{-2} \\x =\frac{- 5 + 4√2}{-2}\end{array} \right.\)
⇔\(\left[ \begin{array}{l} x = \frac{ 5 + 4√2}{2} \\x = \frac{5 - 4√2}{2}\end{array} \right.\)
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