[tex]12^{x^2+5x-4}=12^{2x+6}\iff x^2+5x-4=2x+6\qquad\text{subtract 2x from both sides}\\\\x^2+3x-4=6\qquad\text{subtract 6 from both sides}\\\\x^2+3x-10=0\\\\x^2+5x-2x-10=0\\\\x(x+5)-2(x+5)=0\\\\(x+5)(x-2)=0\iff x+5=0\ \vee\ x-2=0\\\\x+5=0\qquad\text{subtract 5 from both sides}\\\\\boxed{x=-5}\\\\x-2=0\qquad\text{add 2 to both sides}\\\\\boxed{x=2}[/tex]
