Since this is a fairly small equation, it's pretty easy to plug in a few points to get ordered pairs and sketch a graph:
when x = 0... f(0) = 2(0)^2 f(0) = 0 (0, 0)
when x = 1... f(1) = 2(1)^2 f(1) = 2 (1, 2)
when x = -1... f(-1) = 2(-1)^2 f(-1) = 2 (-1, 2)
from there, you can get a rough sketch of the graph just by plotting those points. essentially, it just looks "skinnier" than your typical parabola because the 2 out front makes the curve steeper.
