While doing the transformation f(x)→|f(x)|, we take the mirror image of the graph lying below x-axis and leave the other parts as it is to get the graph of f(x) from |f(x)|
True
|x|=x if x≥0
=−x if x≤0
Similarly,
|f(x)|=f(x) if f(x)≥0
=−f(x) if f(x)≤0
This means, while drawing the graph of |f(x)| from f(x), leave the part where f(x) is positive and change the sign of negative part. Changing the sign (f(x)→−f(x)) is done by taking reflection about x-axis.