Question

Suppose the function shown below was expressed in standard form, y=ax^2+bx+c. What would the value of A be?

A. -2
B. 4
C. 3
D. -1

Answer 1

@LaceyLeanne

Answer 2

Okay:) Glad you mentioned me:) What do you believe the 'a' point is?

Answer 3

I'm not too sure actually. Would 'a' be the highest point?

Answer 4

That's what I was thinking it was...

Answer 5

I'm not sure though, are you? :o

Answer 6

hmmmmm tricky :P

Answer 7

Is there a way for you to look into ur lesson?

Answer 8

No, I can't go back until after I finish a few more questions :(

Answer 9

I figured it out! It was -1 :)

Answer 10

oh okay good job, Im proud.

Answer 11

Thanks!

Answer 12

You too...and for the medal :P

Answer 13

Typically, a quadratic equation can have the form:
\[y=a[k(x-d)]^2+c\]
Where the point \((d,c)\) Is the vertex of the parabola. So in this case, the vertex, is the point \((1,4)\). So we know that:
\[y=a[k(x-1)]^2+4\]

Let us assume that \(k=1\). We can use the point of \((2,3)\). So then:
\[\eqalign{
&y=a(x-1)^2+4 \\
&3=a(2-1)^2+4 \\
&3=(1^2\times a)+4 \\
&3-4=1(a) \\
&-1=a
}\]

Therefore, the equation would be:
\[y=-(x-1)^2+4\phantom{or}or\phantom{or}y=4-(x-1)^2\]