Aparabola with a vertex at (0,0) has a directrix that crosses the negative part of the y-axis. which could be the equation of the parabola? x2 = –4y x2 = 4y y2 = 4x y2 = –4x

In the attached files you can see graphs of all parabolas and their directrices.

As you can see the graph of parabola with a vertex at (0,0) and with a directrix that crosses the negative part of the y-axis is represented at the second diagram.

correct choice is B,

Step-by-step explanation:

Since, if the directrix of a parabola crosses the negative part of the y-axis.

Then it is obvious that the parabola must be upward,

Since, the equation of upward parabola is,

Where, a > 1,

Where (h, k) is the vertex of the parabola,

h = 0, k = 0,

Then the equation of the upward parabola,

∵ a > 0 ⇒ 1/a > 0,

Since, -4 < 0,

Hence, the required equation of the parabola would be,

Note : and have the directrix on the negative x-axis and positive x-axis respectively.

1

step-by-step explanation:

it's the only multiple of both and the least

center (1,3) with radius 6

step-by-step explanation:

we must complete the square to find the center and radius of the circle.

first make sure the x and y squared terms have 1 as their coefficients. we also make sure x and y terms together.

we now create space between the x and y terms with parenthesis.

we complete the square by taking the middle terms -2x and the -6y - divide each and square them.

we add the squares to both sides.

simplify.

and write the quadratics in factored form.

the center is (h,k) or (1,3). the radius is the square root of 36 which is 6.