Question

What number in the vertex form of the equation y= 3(x – 4)^2 + 5 indicates that the parabola opens up?

2

3

4

5

Answer 1

3, it is positive

Answer 2

When you distribute, 3 becomes the coefficient of x^2

Answer 3

The 3 (as pk51 said) is the coefficient of the x^2 term. It determines direction and "thinness" of the parabola. The 4 is a horizontal shift to the right of the vertex. The 5 is a vertical shift up of the vertex.

The 2 tells you that it's a quadratic (and therefore has a vertex at all) :)