Question

The graph below is a parabola, so it can be represented by a quadratic function.



Which of the following quadratic functions could represent this graph?

y = -( x + 2) 2 + 4
y = ( x - 2) 2 + 4
y = -( x - 2) 2 - 4
y = -( x - 2) 2 + 4

Answer 1

please post the graph

Answer 2

Do you know the standard form of quadratic function?

Answer 3

Can you add it here please?

Answer 4

The vertex form

Answer 5

The standard vertex form

Answer 6

Good, now you need to determine the vertex on the graph, can you do that?

Answer 7

Please show

Answer 8

4 is one of the coordinates, the y, what about the x-coordinate of same point?

Answer 9

Imagine a vertical line from that point, what would be the intersection point with x-axis?

Answer 10

Excellent, you have (h, k) = (2, 4)

Answer 11

Now, what would be the leading coefficient a? Is it positive or negative?

Answer 12

Positive?

Answer 13

Look at the graph, if the graph is U-shaped, then a would be positive, otherwise its negative.

Answer 14

oooh okay

Answer 15

So, what it your answer choice, after you determined that, a = -1, h = 2, k = 4?

Answer 16

y=-(x+2)^2+4

Answer 17

Substitute the values into vertex form you gave above

Answer 18

y=-(x-2)4=x?

Answer 19

or um y=-(x-2)2^+4

Answer 20

Congrats, its correct

Answer 21

omg thank you

Answer 22

You are welcome! Hope you can solve similar problems yourself

Answer 23

Thank you =]