Show that the mapping $I : C^0(\Bbb R) → C^1(\Bbb R)$ defined by $I(f)(x) =\int_2^x f(t)dt$ is a linear transformation.
Am I just proving that $I(v+w)= I(v)+C(w)$ and $I(cv)=cI(v)$?
And would that just involve replacing the x in the integral with $u$ and $v$?
No. Here $u$ and $v$ are elements of $C^0(\Bbb R)$, not $\Bbb R$.
Show that $$\int_2^x (cu)(t)dt=c\int_2^x u(t)dt$$ and $$\int_2^x (u+v)(t)dt=\int_2^x u(t)dt+\int_2^x v(t)dt.$$