What is the possible discriminant of the graph?

Question

a parabola opening up with vertex near negative 1.2 comma negative 9.1. a y intercept of negative 6

 

Choose one answer.
A. -11
 

B. zero
 

C. 25
 

D. 73

Answer 1

For a parabola with a vertex at (-1.2, -9.1) and a  y intercept = -6, one wants to express the equation as  y=a(x-h)^2 + k, where (h,k) is vertex, so h=-1.2 and k=-9.1.

 

so:  y=a(x-h)^2 + k = a(x- (-1.2))^2 + (-9.1)

y = a(x + 1.2)^2 - 9.1

 

Now you still have the unknown a, but you know an (x, y) that satisfies the equation, namely the y-intercept (0, -6).  Let's plug these into the equation to solve for a:

 

-6 = a(0 + 1.2)^2 - 9.1

-6 + 9.1 = a(1.2)^2

3.1 = a * 1.44

a = 3.1 / 1.44 = 2.15

 

So the equation is y=2.15(x + 1.2)^2 -9.1

 

Now there is something missing in your statement of the problem.   What do the possible answer have to with the parabola?