How do you graph the parabola y=(x+4)23 using vertex, intercepts and additional points?

1 Answer
Jun 23, 2016

First: Notice the form
Second: Solve for the intercepts
Third: Pair up

Explanation:

  1. Notice The Form
    Recall that the general forms of the parabola are:
  2. (±yk)2=(xj) opening to theleft/right
  3. (yk)=(±xj)2 opening up/down
      *where (j,k) is the vertex of the parabola
    

Note that the given follows the form of opening up/down. Additonally, its form follows the opening up parabola since the given has a positive 'x' component. Also we now know that the vertex of the parabola is at (-4,-3).
How?
By rearranging the given, we can see the general form:
y+3=(x+4)2
y(3)=(x(4))2

Hence, the verex is at (-4,-3).

  1. Solve For The Intercepts

For the x-intercept, let x=0

y=(0+4)23
y=163
y=13

Hence, the x-intercept is at (0,13).

Next is the y-intercept. Let y=0.

0=(x+4)23
3=(x+4)2
±3=x+4
4±3=x
x=4±3

Hence, the y-intercepts are at (-4-√3,0) and (-4+√3,0).

  1. Pair Up.

Choose any number as your x and substitute it into the given equation. Then, pair the chosen x's to their corresponding solution.

Example:
Let x=1

y=(1+4)23
y=523
y=253
y=22

Thus, the pairing would be: (1,22). And so on.

Hope this helps!