Answer:
y = 2x^2 is a parabola opening up with it's vertex at (0,0)... y=3x^2 -4 is also a parabola opening up, but it is 'thinner' in that it rises in y faster and it's vertex is at (0,-4)
Step-by-step explanation:
all equations of the type y = ax^2 + b are parabolas centered on the y-axis, soo the vertex is always on (0,b)
If a is positive then the parabola opens up,
the bigger a is, the 'thinner' the graph is, i.e. the faster the graph rises
the value of b determines the location of the vertex, if b is added, then the vertex rises over the x-axis, if b is subtracted then the vertex is below the x-axis
-2y>12x-42
y<21-6x
so a is true
7 + (0-7) * 2/3 = 7 - 14/3 = (21 - 14) / 3 = 7/3 = 2.3
Where r is the radius of the circle.
