Question

Without drawing the graph of the equation, determine how many points the parabola has in common with the x-axis and whether its vertex lies above, on, or below the x-axis.

y = –2x^2 + x + 3

A. 1 point in common; vertex on x-axis

B. 2 points in common; vertex below x-axis

C. 2 points in common; vertex above x-axis

D. no points in common; vertex below x-axis

Answer 1

We know it's a parabola because it's a second degree polynomial. Is it facing up or down?

Answer 2

down?

Answer 3

Yup. But that + 3 on the end moves the parabola up three units.

How many times must it intersect the x-axis?

Answer 4

C?

Answer 5

A parabola looks kind of like an open U. If the parabola's vertex is on the origin it intersects only once no matter which direction it's facing

but since that +3 moves it up 3 spaces how many times should it touch the x-axis?

Answer 6

1