Advanced shifting functions

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Several transformations can be combined into one form: g(x)=a f(x−h)+kg(x) = a\,f(x - h) + k.
Each piece does a separate job, and reading them one at a time keeps it simple.
The changes inside the function affect the graph horizontally, and the changes outside affect it vertically.
The (x−h)(x - h) inside causes a horizontal shift, and its sign is opposite to what it looks like.
So f(x−3)f(x - 3) moves the graph 33 units to the right, while f(x+3)f(x + 3) moves it 33 units to the left.
The aa in front is a vertical stretch, and a negative aa also flips the graph over the xx-axis.
The +k+ k at the end is a vertical shift: +k+k moves the graph up by kk, and −k-k moves it down.
For example, 2f(x)−12f(x) - 1 makes the graph twice as tall and then lowers it by 11.
For a parabola, this form is especially useful and is called vertex form: y=a(x−h)2+ky = a(x - h)^2 + k.
Its vertex sits exactly at (h,k)(h, k), so y=(x−2)2+1y = (x - 2)^2 + 1 has its vertex at (2,1)(2, 1).
vertex_form.png
When several changes appear together, apply them in order.
Take g(x)=−f(x+1)−4g(x) = -f(x + 1) - 4: the +1+1 inside shifts ff left 11, the minus sign flips it over the xx-axis, and the −4-4 lowers it by 44.
Handling one piece at a time avoids mixing up the directions.

Worked examples

How does g(x)=f(x−3)+2g(x) = f(x - 3) + 2 transform the graph of f(x)f(x)?
The −3-3 inside shifts the graph 33 units to the right, and the +2+2 outside shifts it 22 units up.
So gg is ff moved right 33 and up 22.
Where is the vertex of the parabola y=2(x−1)2−4y = 2(x - 1)^2 - 4?
In vertex form y=a(x−h)2+ky = a(x - h)^2 + k, the vertex is at (h,k)(h, k).
Here h=1h = 1 and k=−4k = -4, so the vertex is at (1,−4)(1, -4).
The graph below shows a function f(x)f(x) and its transformation g(x)=−f(x+2)−1g(x) = -f(x + 2) - 1.
advshift_ex3.png
How does gg transform f(x)f(x)? \ The +2+2 inside shifts ff left 22, the minus sign flips it over the xx-axis, and the −1-1 lowers it by 11. \ So gg is ff reflected over the xx-axis, shifted left 22, and down 11.

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