f(x) has the smallest minimum. The minimum value of f(x) is -3
The largest sin(x) can get is 1.
This applies to sin(2x-pi) as well. So f(x) is as small as -5*(1)+2 = -5+2 = -3.
You can see this each time the red curve bottoms out at y = -3.
The smallest that g(x) can get is y = -2 as shown at the vertex (3,-2)
The smallest that h(x) can get is y = 3 as shown by the point (1,3)
See the attachment for a visual comparison of the three functions.
