From Förberedande kurs i matematik 1
The curve
y=x2
is a parabola with a minimum at the origin according to the figure below on the left and, compared with that curve,
y=x2+1
is the same curve but with the number
1
added to the
y
-coordinate of each point, i.e. the parabola is shifted one unit up in the
y
-direction.