Why has it been necessary to make so many changes to our paper currency in the past 30 years as compared to the last 100 years?

Criminalnology is an empirical science which encompasses the following areas of study

How has naturalization made an impact or change in society, government, and the political process?

Which of the following is a polynomial with roots 3,5i, and -5if(x)=x^3-3x^2+25x-75f(x)=x^3-3x^2+15x-25f(x)=x^3-15x^2+25x-75f(x)=x^3-3x^2+15x-75