Solving f(x)=g(x) using the graphic representations of these functions is to see for which x, f and g intersect

f(x)=g(x) <=> x=-2 or x=-1 or x=0 or x=1 or x=2 or x=3

However these functions are may not only exist for x between -3 and 3 as ploted. We could "see" that f and g will intersect also for x=4,-4,5,-5 sor for all values of x that equals an integer.