\(2.3^{x+3}=10.3^{12}+8.3^{12}\)
\(\Leftrightarrow2.3^{x+3}=18.3^{12}\)
\(\Leftrightarrow3^{x+3}=9.3^{12}\)
\(\Leftrightarrow3^{x+3}=3^{14}\)
\(\Leftrightarrow x+3=14\Leftrightarrow x=11\)
\(\Leftrightarrow2\cdot3^{x+3}=3^{12}\cdot18\\ \Leftrightarrow2\cdot3^{x+3}=3^{14}\cdot2\\ \Leftrightarrow x+3=14\Leftrightarrow x=11\)
2.3x+3=10.312+8.3122.3x+3=10.312+8.312
=2.3x+3=18.312⇔2.3x+3=18.312
=3x+3=9.312⇔3x+3=9.312
=3x+3=314⇔3x+3=314
=x+3=14⇔x=11