How many planes contain the same three collinear points?

infinitely many

Step-by-step explanation:

well if you think about it in a 3D plane

we can make to planes intercept at a line

and we can make another plane that another plane interceptes the other to planes in the same line

and another

and another

...

so we can have three points in the line (collinear) that the planes intercept and we are done

h is the x-coordinate of the vertex

step-by-step explanation:

we have

in this function

the point represent the vertex of the function

so

h is the x-coordinate of the vertex

k is the y-coordinate of the vertex