Question

Graph the parabola.

y=-2x²
Plot five points on the parabola: the vertex, two points to the left of the vertex, and two points to the right of the vertex. Then click on the graph-a-function
button.

Answer 1

The vertex is found by finding the x-coordinate first:

x = -b / 2a

x = -0 /2(-2) = 0

Plug x=0 back in to find the y-coordinate of the vertex:

y = -2(0)^2 = 0

The vertex is (0,0).

Now pick any two x-values to the left of 0 and any two to the right and calculate the y-values:

x = -1

y = -2(-1)^2 = -2

(-1, -2)

x = -2

y = -2(-2)^2 = -8

(-2, -8)

x = 1

y = -2(1)^2 = -2

(1, -2)

x = 2

y = -2(2)^2 = -8

(2, -8)

Plot those 5 points and you're done.