y = -0.05x^2 +x + 3 relates the height of the marshmallow to the horizontal distance it has travelled. It can be written in function notation as follows:
f(x) = -0.05x^2 + x + 3. To find the initial height of the marshmallow we plug in f(0).
f(0) = -0.05(0) + 0 + 3
f(0) = 3
An alternative way to solve this problem is to just look at the term with no variable attached. This is the initial position.