\(\Leftrightarrow4x^2-9-4x^2+4x=7\\ \Leftrightarrow4x=16\\ \Leftrightarrow x=4\)
\(\Leftrightarrow4x^2-9-4x^2+4x=7\\ \Leftrightarrow4x=16\Leftrightarrow x=4\)
⇔x[(2x)2 - 9] - (4x2 - 4x)=7
⇔x(4x2 - 9) - (4x2 - 4x)=7
⇔ 4x3 - 9x - 4x2 + 4x = 7
⇔ 4x3 - 4x2 - 5x - 7 = 0