Y=x^2 + 1 why is this function nonlinear?

Its non linear because of the x squared. This would indicate an ever increasing answer, not one that has a constant rate. This equation would be quadratic.

what is the original number? you forgot to add it.

if you are saying purchasing 3 social media ads and one newspaper ad counts as one purchase then there are:

6 purchases

if you are asking how many of each then:

18 social media ads

6 newspaper ads