Consider adding a number
k to a function rule.
g(x)=f(x)+k
If
k is , this operation increases the value of the output for every
x, moving the graph upward. Similarly, if
k is , then the graph is moved downward, because the of the function is decreased.
Now consider subtracting a number
h from the input.
g(x)=f(x−h)
If
h is positive, then the value of the input is reduced. Therefore, greater
x-values are needed to obtain the original output, leading to a translation to the right. In contrast, when
h is negative, the input value is increased. This means that smaller inputs are needed to obtain the original output. This leads to a translation to the left.