Tìm x biết: 16x^2 - 9(x + 1)2 = 0
Tìm x biết: 16x2 – 9(x + 1)2 = 0.
16x2 – 9(x + 1)2 = 0
⇔ (4x)2 – [3(x + 1)]2 = 0
⇔ (4x)2 – (3x + 3)2 = 0
⇔ (4x – 3x – 3)(4x + 3x + 3) = 0
⇔ (x – 3)(7x + 3) = 0
⇔ \(\left[ \begin{array}{l}x - 3 = 0\\7x + 3 = 0\end{array} \right.\)
⇔ \(\left[ \begin{array}{l}x = 3\\x = \frac{{ - 3}}{7}\end{array} \right.\)
Vậy x = 3 hoặc \(x = \frac{{ - 3}}{7}\).