Use the quadratic formula to solve the equation.
x^2-x=-2
Please help, I dont' know why this one is so confusing to me, but I can't get it.

- anonymous

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- Callisto

x^2-x=-2
x^2-x+2 =0
ax^2 +bx +c =0
\[x=(-b \pm \sqrt{b^2-4ac)}/(2a)\]

- Callisto

put the corresponding value to the formula

- anonymous

x^2-x+2=0
Use quadratic formula:
ax^2-bx+2=0
a=1, b=-1, c=2

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## More answers

- anonymous

so the x's are equal to 1 right?

- Callisto

since Δ<0, you will not get real solutions..

- Callisto

i is the imaginary number\[i=\sqrt{-1}\]

- anonymous

so was my answer close? I thought I was completely wrong and deleted it.

- Callisto

Hmm.. close but not correct... don't be afraid to make mistakes!

- anonymous

Sorry this is really confusing to me.

- Callisto

So, can you try again to get the answer?

- anonymous

I can try, but I don't understand still how it works. With no real numbers, it totally confuses me.

- Callisto

show you steps please~

- anonymous

trying to go over every thing you have said so far to see if I can comprehend it.

- Callisto

i deleted my answer.. i hope you can try...perhaps you can start with substituting the numbers into the formula and ask whatever you don't understand so we can help

- anonymous

I don't understand the imaginary number. Where does that come in?

- anonymous

what is the formula I need to use?
Is it the ax^2+bx+2?

- Callisto

ax^2 +bx +c =0 is the general form of a quadratic equation. Before you apply the quadratic formula, you have to make the equation into general form first

- Callisto

then use the quadratic formula
\[x=(-b \pm \sqrt{b^2-4ac)}/(2a)\]

- anonymous

Ok now my nerves are gone. I have gone beyond confusion now. LOL

- Callisto

that means you understand it now?

- anonymous

so when you say to put it into general form...you mean its not already in general form the way that it is?

- anonymous

No that means that confusion is an understatement. Now I am just plain lost!

- Callisto

x^2-x=-2
it is not in a general form

- Callisto

but when you add 2 on both sides, it is in the general form

- anonymous

ok

- Callisto

so you 'll get x^2 -x +2 =0

- anonymous

right ok I got that.

- Callisto

match the coefficient with a, b,c in the general form

- Callisto

a=1, b=-1, c=2

- Callisto

Then put these value into the quadratic formula, and you'll get x

- Callisto

*values

- anonymous

so do I really put in the numbers 1 when putting the values into the formula?

- Callisto

put a=1, b=-1, c=2 into the formula

- anonymous

ok got that...here is what it looks like;
|dw:1332557688893:dw|

- Callisto

you missed something
|dw:1332557777618:dw|
Try again~

- anonymous

|dw:1332557813720:dw|

- Callisto

|dw:1332557876749:dw|

- anonymous

so if its not -1 then what is it? do I leave it as -b?

- Callisto

b=-1, -b = -(-1) =1

- anonymous

I am sorry. I am confused. I don't get this. Sorry for wasting your time.

- anonymous

negative and a negative make a positive....I see it now.

- Callisto

understand?

- anonymous

Getting there slowly. I am sorry.

- anonymous

Now this is what I have: |dw:1332558245309:dw|

- Callisto

|dw:1332558287195:dw|

- anonymous

thats the answer? is there more i need to do?

- Callisto

have you learnt imaginary number i?

- anonymous

Yes, but I don't get it either. Don't understand the point in it.

- Callisto

\[i=\sqrt{-1}\] understand?

- anonymous

um....yeah.

- Callisto

\[\sqrt{ab} = \sqrt{a}\times \sqrt{b}\]understand?

- anonymous

yes

- Callisto

\[\sqrt{-7}=\sqrt{-1\times7} =?\]

- anonymous

\[\sqrt{-7}i\]

- Callisto

nope.. slowly, use the formula above..

- anonymous

well -1*7=-7

- Callisto

Yup...\[\sqrt{-7}=\sqrt{-1\times7} = \sqrt{-1}\times \sqrt{7} \]

- Callisto

understand?

- anonymous

yes

- Callisto

what is the next step?

- anonymous

multiply the square roots?....\[\sqrt{-1}*\sqrt{7}\]

- Callisto

yup... then?

- Callisto

what is\[\sqrt{-1}\]?

- anonymous

i

- Callisto

hmm.. draw you conclusion to\[\sqrt{-7}\]

- anonymous

|dw:1332558977446:dw|

- Callisto

nope...\[\sqrt{-1\times7}=\sqrt{-1}\times \sqrt{7} =?\times \sqrt{7}\]what is that question mark ?

- anonymous

\[\sqrt{-7}\]

- Callisto

|dw:1332559217214:dw|

- anonymous

ok \[\sqrt{-1}=i\]
I don't guess I am seeing what your getting at.

- anonymous

Your seriously gonna have to dummy it up a bit, b/c I really don't get this stuff very easily. I have been lucky to make it as far as I have in Algebra without totally failing.

- Callisto

|dw:1332559433395:dw|

- anonymous

Ok whew...that was frustrating, my brain hurts. So then the answer I am looking for on my problem would be....|dw:1332559544375:dw|

- Callisto

|dw:1332559618800:dw|

- anonymous

and thank you for being patient and putting up with a math illiterate student.

- Callisto

it'd be better if you can practise more...

- anonymous

Yeah this is my final exam and then I am done with math. Thank you so much for your help...i really appreciate it. REALLY!!!

- Callisto

yw

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