Question

What is the focus of the following graph?

Answer 1

(5, 0)

(0, 5)

(4, 0)

(0, 4)

Answer 2

Parabolas. The directrix is 5 units away from the vertex. That means the focus must be 5 units away in the opposite direction. So...if the vertex is (0,0) and it's 5 units to the right, that means it's (0+5,0)
What is (0+5,0) simplified?

Answer 3

If the directrix of the parabola is at x=a, then the focus = (-a,0)

what's 'a' then?

Answer 4

so its B?

Answer 5

its (5,0)

Answer 6

general form of this parabola is y^2 = 4ax
as you see from graph y=about 9 when x = 4
so 81 = 4*4 * a
a = 81/16 = 5 to nearest whole number

Answer 7

thankss