Answer:
x=0.27
Step-by-step explanation:
We are given the equation;
[tex]1.2*10^{4x}-4.2=9.9[/tex]
The first step is to add 4.2 on both sides of the equation;
[tex]1.2*10^{4x}=14.1[/tex]
The next step will be to divide both sides of the equation by 1.2;
[tex]10^{4x}=11.75[/tex]
Next we take natural logs on both sides of the equation;
[tex](4x)ln10=ln11.75[/tex]
Finally, we divide both sides by 4*ln10 and simplify to determine x;
[tex]x=\frac{ln11.75}{4ln10}=0.27[/tex]