Answer:
x=0.27
Explanation:
We are given the equation;
![1.2*10^(4x)-4.2=9.9](https://img.qammunity.org/2020/formulas/mathematics/high-school/3wantsq277i85htufqb4ojm1aapiiz071c.png)
The first step is to add 4.2 on both sides of the equation;
![1.2*10^(4x)=14.1](https://img.qammunity.org/2020/formulas/mathematics/high-school/e37iudu7cclvcazzz78qubn4a5f6ywd1v8.png)
The next step will be to divide both sides of the equation by 1.2;
![10^(4x)=11.75](https://img.qammunity.org/2020/formulas/mathematics/high-school/ikp1s3gbmen0mbk3c5bn4ewga4xygpdq9o.png)
Next we take natural logs on both sides of the equation;
![(4x)ln10=ln11.75](https://img.qammunity.org/2020/formulas/mathematics/high-school/jb1466j7b1eei5o7dz69bybgmrlii5om8a.png)
Finally, we divide both sides by 4*ln10 and simplify to determine x;
![x=(ln11.75)/(4ln10)=0.27](https://img.qammunity.org/2020/formulas/mathematics/high-school/2h0a214sfd6hni1qxhue7nmv01voycdd5b.png)