Question

Which equation represents a parabola opening to the left with a vertex at the origin and a focus at (-7, 0)?

Answer 1

Answer:

b. x=1/28 y^2

Step-by-step explanation:

the standard equation,

                      $y^{2} = 4ax$  ---(1)    , when opening towards left or right

                      focus at (a , 0)

                      $x^{2} = 4ay$ ---(2)      , when opening towards top or bottom

                      focus at (0,  a)

                                             

if a is negative parabola will open toward negative axes ( down or left) and vice versa.

re- arranging option b. we get

                        $y^{2} =28 x\\y^{2} = 4 X (-7 x)$ -----(3)

therefore, a =  -7

(3) is similar to (1)

So it is facing left with focus at (-7,0)