$\int f(x)\,\mathrm{d}x = \left(\int_0^x f(t) \, \mathrm{d}t\right) + C$ If $f(x)$ is a continuous function on $\mathbb{R}$ and I am asked to find 
$\int f(x) \, dx$, what is the problem with the following answer:
$$\int f(x)\,\mathrm{d}x = \left(\int_0^x f(t) \, \mathrm{d}t\right) + C$$

Despite teaching calculus for 20+ years, I have never seen a student do this on an exam, so the novelty of seeing it for the first time would count for something. The first time I would see it, I would accept it and even be somewhat impressed with the student. Far too few students really understand that part of the fundamental theorem of calculus. The second time I would see it, I would suspect that a thoroughly unimpressive student heard about how to get credit for no work. Their plan would backfire and they would get no credit for the problem. 
