Question

Is this -.81?

Answer 1

@mathmale

Answer 2

\[C = (\frac{ b }{ 2 }) ^2\]

Answer 3

Divide 12 by 2, you get 6, square 6, you get 36

Answer 4

Try to apply what you leared in previous problems like this one. As ShadowLegend points out, you take the coefficient of the x term (which is 12), halve it (getting 6) and squaring this result. Both add and subtract 36 to the left side of this equation.

Answer 5

...what you learned...

Answer 6

I'm confused as to why you ask this "Is this -.81?"

Can you explain how you got that number?

Answer 7

The number you add to both sides is 36 though, as per my steps I showed for you earlier.

Answer 8

So 36

Answer 9

No @ShadowLegendX that is what I thought that -.81 is incredibly wrong. but somebody on here was saying that was the correct answer and was giving me explanations for it as well. That is why I got confused

Answer 10

Oh, where did he/she give this answer? I would like to see their explanation

Answer 11

On my previous post, I can taG you

Answer 12

Shadow is correct.
You must learn the "completing the square" procedure. Shadow has laid that out step by step.

Identify the coefficient of the "x" term. Since the "x" term is 12.
Take half of that. What do you get?

Please, take notes on this conversation. it is critically important that you be able to transfer what you've learned in previous problems to new problem situations.

what is "half of the coefficient of x in the given equation?"

Answer 13

Is it 6?

Answer 14

Yes, it's 6. Now please square 6. 6^2=?

Answer 15

Well I learned something to complete the square for any polynomial of the form x^2+bx it would be (b/2)^2

Answer 16

That is EXACTLY what we are doing here. NOTHING different about that. Please,
square 6, OK? 6^2 = ?

Answer 17

36?

Answer 18

"b" represents the coefficient of the "x" term and is 12.

Half of 12 is 6

What is the square of 6?

Answer 19

3?

Answer 20

@mathmale

Answer 21

What does "square" mean?
What does "square root" mean?

I'm afraid you have these mixed up.

What is the square of 6?

Do you have a calculator handy?

Answer 22

oh 6^2

Answer 23

36 =)

Answer 24

Yes, and what is 6^2? Yes, 36.

OK. You began with x^2+12x=-9.
Rewrite this with some space after x^2+12x: x^2+12x =-9
Now add 36 to x^2+12x, and then subtract 36 from your result.
Show your work. Think carefully before doing anything.

Answer 25

x^2+12x=-45?

Answer 26

Where did the -45 come from?

For now, please try to follow my instructions exactly. I asked you to modify ONLY the left side of the equation x^2 + 12x = -9

Answer 27

Try again.

Starting with x^2 + 12x =-9,

add 36 to x^2 + 12x and then subtract 36 from your result. Do NOT touch the '-9."

Answer 28

Oh okay so it would be x^2+12x-36?

Answer 29

I apologize I jumped a little ahead of myself

Answer 30

You have a tendency to do more than you are asked to do. For now, please, please follow my instructions. You can play around with this all you want later, but we need to come to closure onthis particular problem. Try again.

Answer 31

Start with x^2 + 12x =-9
Add 36, and then subtract 36, to and from x^2 + 12x.

Answer 32

So add 36 to x^2+12x right?

Answer 33

that's part of it, but not the complete answer. Please go back and re-read my directions. It would not help you if I were to repeat the same instructions again.

Answer 34

Hint: What does "add 36, and then subtract 36, from ... " mean? Think about it.

Answer 35

You end up with 0?

Answer 36

@mathmale

Answer 37

Here, "add" means to actually write in "36," and following that, write in "-36."

We have been thru this before.

x^2 + 12x + 36 - 36 = -9.

Notice how I have "added 36 to x^2+12x and then subtracted 36 from the result."

Copy this result. rewrite (x^2 + 12x + 36) as the square of a binomial:

example: (x-3)^2 is the square of a binomial (but not the answer to YOUR homework problem).