Question

Compare and contrast the two quadratic equations below. In order to receive full credit, use complete sentences to describe the following:

The direction each parabola opens
The vertex of each parabola

y = x2 − 4x
y = −2x2 + 8x − 12

@jim_thompson5910

Answer 1

what did you get

Answer 2

#1 is up and #2is down, i just dont know the vertex

Answer 3

both are correct

Answer 4

to find the vertex, you need to find the x coordinate of the vertex first

Answer 5

so you use this formula

x = -b/(2a)

Answer 6

Can you help me by setting them up.

Answer 7

the first equation, what are the values of a, b, c?

Answer 8

a is x and b is 4, but there isn't a c.

Answer 9

not really

Answer 10

y = x^2 − 4x

is the same as

y = 1x^2 − 4x

Answer 11

so a = 1 and b = -4, c = 0

x = -b/(2a)

x = -(-4)/(2*1)

x = 4/2

x = 2

Answer 12

So, number one is 2?

Answer 13

so the x coordinate of the vertex is 2

if x = 2, then y = ???

Answer 14

2?

Answer 15

y = x^2 − 4x

y = (2)^2 − 4(2)

y = 4 - 8

y = -4

See how I'm getting this?

Answer 16

Ohh, yeah. >.< I messed up. Thanks for showing me :)

Answer 17

sure thing

so what this all means is that the vertex of y = x^2 − 4x is (2, -4)