\begin{gathered}(3x + 2) {}^{2} - 9x {}^{2} = 9x + 7 \\ 9x {}^{2} + 12x + 4 - 9x {}^{2} = 9x + 7 \\ 12x - 9x = 7 - 4 \\ 3x = 3 \\ x = 1\end{gathered}
(3x+2)
2
−9x
=9x+7
9x
+12x+4−9x
12x−9x=7−4
3x=3
x=1
\begin{gathered}(3x + 2) {}^{2} - 9x {}^{2} = 9x + 7 \\ 9x {}^{2} + 12x + 4 - 9x {}^{2} = 9x + 7 \\ 12x - 9x = 7 - 4 \\ 3x = 3 \\ x = 1\end{gathered}
(3x+2)
2
−9x
2
=9x+7
9x
2
+12x+4−9x
2
=9x+7
12x−9x=7−4
3x=3
x=1