I like to think in terms of where a certain point gets mapped to when you transform the graph. So for example, take f(x) = sin(x) and then consider g(x) = a*sin(b*x). Well first consider h(x) = a*sin(x). The point (pi/2, 1) gets mapped to (pi/2, a). Then consider j(x) = sin(b*x). The point (pi/2, 1) gets mapped to ( (1/b) * (pi/2), 1). Combining, for g(x) the point (pi/2, 1) gets mapped to ( (1/b) * (pi/2), a).

So in general (x,y) becomes (x/b, a*y).

This means we can sketch this graph.

Here, a = 50 and b = 4.2*10^2 (assuming I interpreted your parentheses properly).