Shifting of graph of function $y = f(x)$ to $y = f(x – c)$

algebra-precalculusfunctionsgraphing-functionstransformation

I am trying to understand if we have $y = f(x)$, then consider the function $g(x) = f(x – c)$ translate $y = f(x)$ to the right by c. I understand that if we put $x = c + j$, then we have $f(j) = g(c + j)$, so everything is shifted to the right by c. When I saw this initially it seemed to me that $g(x)$ shifts to the left instead of the right. Why are we getting this difference in x-axis and y-axis shifts? For instance, if we set $h(x) = f(x) – c$ we shift $h(x)$ downards?

Best Answer

When we put $x-c$ rather than $x$ inside the function we need $x$ to be higher to get the same result.

When we write $y=f(x)-c$ we have $f(x)=y+c$ and we need $y$ to be lower to get the same result.

I used the second formulation for the second example to be consistent, so that the shift $c$ appeared in the same part of the equation as the variable $y$ which is shifted.

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