Does anyone know a piece of advice, how to draw graphs like
abs(y)=1-x^2?
thanks
$\displaystyle |y|=1-x^2$ just meas that $\displaystyle y=1-x^2$ or $\displaystyle -y=1-x^2$.
Therefore you can just draw the graph of $\displaystyle y=1-x^2$, and then draw that graph again, but flipped around the x-axis (which changes the sign of the y-coordinates only).
Of course, the resulting figure is not the graph of a function, but it is the graph of a relation (between x and y).