For the first equation:
[tex]f(x)=-x+5,g(x)=2f(x)[/tex]That's a vertical stretch by 2. If you change f(x) for 'y' you'll see that more clearly:
[tex]y=-x+5,g(x)=2y[/tex]All 'y' coordinates of the function are now twice as before. This means that the function is stretched vertically.
For the second:
[tex]f(x)=x-4,g(x)=-f(x)[/tex]We'll change f(x) for 'y' too:
[tex]y=x-4,g(x)=-y[/tex]That is a reflection over the x axis. This is because in order to go from y to -y all 'y' coordinates of the points on the function have to change from possitive to negative and from negative to possitive. In a graph:
