# algebra

posted by
**lee**
.

Can someone check my answers please and if Im wrong please explain.

1) graph 4x^2+4y^2=64. what are the domain and range?

domain;all real numbers

range;-4<=4<=4

2) graph 4x^2+y^2=9. what are its lines of symmetry?

it has two lines of symmetry, the x axis and the y axis

3) graph -3x^2+12y^2=84. what are the domain and range?

domain; all real numbers

range; {y[y<=-sqrt7 or y>= sqrt7}

4) identify the center and intercepts of the conic section. then find the domain and range.

the center of the circle is (0,0)

the x intercepts are (6,0) and (-6,0)

the y intercepts are (0,6) and (0,-6)

the domain is {x[-6<=x<=6}

the range is {y[-6<=y<=6}

5) write an equation of a parabola with a vertex at the origin and a directrix at y=5.

y=-1/20x^2

6) what are the focus and the directrix of the graph of x=1/24y^2?

focus(6,0)

directrix x=-6