Question

Given u(x)=x+3 and v(x)=9x-4 find u+v

Answer 1

The sum function $(f+g)(x)$ is defined exactly as the sum of the two functions:

$(f+g)(x) = f(x)+g(x)$

So, you simply have to sum the expressions:

$(u+v)(x) = u(x)+v(x) = (x+3)+(9x-4) = 10x-1$