Question

Am I correct on 13???

Answer 1

Answer:

  yes

Step-by-step explanation:

If you like, you can start with ...

  y = x^2

which goes through points (-1, 1) and (1, 1).

You can scale it horizontally by a factor of 10 (so it is 20 units wide) by replacing x by x/10. And you can scale it vertically by a factor of 5 by multiplying the function by 5. Together, these scalings give ...

  y = 5(x/10)^2 = (1/20)x^2

The leading coefficient can be written as 1/(4p) with p=5. This (p) is the distance from the vertex to the focus. Since we want the microphone to be located at the focus, it will be 5 inches from the bottom of the dish.