Question

How to write: y=ax^2+bx+c by completing the square and writing it in vertex form ?

Answer 1

start by setting y = 0

(1) ax^2 + bx + c = 0

c is just a constant, move it to the other side (we're solving for x).

(2) ax^2 + bx = -c

To complete the square we need the x^2 to be by itself, divide a to get rid of it.

(3) x^2 + (b/a)x = -c/a

Take half the x term (b/2a) and square it: (b/2a)^2 --->(b^2)/(4a^2)

add the last step to both sides of step (3)

(4) x^2 + (b/a)x + (b^2)/(4a^2) = -c/a + (b^2)/(4a^2)

I'll continue the rest in another post...typing equations sucks.

Answer 2

oh okay! You can draw it if thast easier![=

Answer 3

I think I might do that. :)

Answer 4

ok!!

Answer 5

Sorry that took long too.

Answer 6

thxn :DD

Answer 7

wait but how would you write that in vertex form?

Answer 8

Sec. I misread your initial question

Answer 9

oh alrighty ~

Answer 10

The vertex form of a quadratic is given by y = a(x – h)2 + k, where (h, k) is the vertex. The "a" in the vertex form is the same "a" as in y = ax^2 + bx + c

(that is, both a's have exactly the same value). The sign on "a" tells you whether the quadratic opens up or opens down.

So...

Answer 11

Lol. I need to get a new paper out. You better become my fan after this one. :)

Answer 12

lol ok (x

Answer 13

I'm going to go ahead an omit the explanation this time. But I will number each step so you can ask me questions on what I did, if you get lost.

Answer 14

Here you go.

Answer 15

thnx so very much!

Answer 16

You're welcome. :)

Answer 17

&& the axus of s is simply -b/2a=x

Answer 18

@ajmayberry