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So, I need a little help.

Find x.

x^2 - 4x + 4 = 9

Could someone help me, shouldnt take more then a few seconds.

5?

I'm bad at math but i'm trying to figure it out anyways. =X
edit: 6?

i can do it, but someone will post before i get a pen out -.-

we are doing that stuff in school atm

lol.

5^2 = 25
5*4 = 20

25-20+4=9

so i was right me thinks

As far as I know this is how you do it, but I think im wrong.

x^2 - 4x + 4 = 9

(x - 4)^2 = 9

x - 4 =+-3

x1= 7
x2= 1

what does the ^ do?

x1 and x2 should be same number but 1 = + and 2 = -

>.O?

huh O.o

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

so how can x^2 be (x-4)^2

-9 from the right
x^2-4X-5=0
then factor:
(x+1)(x-5)=0
x=-1
x=5
i think , my algebra brain isnt working after geometry

Its the right answer but I dont get it. lol.

where does the"(x+1)" come from?

49 - 36 + 4 = 17

x=5
x=-5

25 - 20 + 4 = 9
25 - 20 + 4 = 9

I havent actually worked it out, but thats just using trial and error

This is right 100% . Just gonna explain it to you by steps i guess.

1) x^2 - 4x + 4 = 9
--> Rearange equation.
x^2 - 4x - 5 = 0

2) Now solve for x.
x^2 - 4x - 5 = 0
(x - 5) (x+1)

3) Now you have got ur x values. x = 5 or x = -1

You can substitus these x values into the equation and see it yourself.

after subtracting 9, u get X^2-4X-5=0 right?
well, u have to get that to a (X+#)(X-#)=0, which is EDIT: FACTORING!!
so, u take the -4x and -5, and see which 2 numbers multiply to -5 and add to -4, in this case, 1 and -5
so, that fills in to (X+1)(X-5)=0
then u no that u need to multiply something by 0 to get 0, so u take the opposite of any of the #s, in this case, -1 and 5

i dont really no how to explain it very well =.=
the # with an X is the one that the 2 numbers must ADD up to, and the one with out an X is the one they must MULTIPLY to

If you put -5 into the equation, you woulnt get -20, you would get +20.

time for bed =_=

thnx guys

San is right ... it's just simple factoring

i thought this was 0l3n's question
why are u thanking us?

lol, i called it oversimplifying
its factoring, thanks silkroad

maths make me sleepy

night night <3

x = 5
x = -1

Rewrite the equation as x^2 - 4x - 5 = 0.

You can then write the equation as (x - 5)(x + 1) = 0.

So yeah, what San said.

rest easy cin

i didnt ace algebra for nothing!

this is like 3th grade maths :p

it's kinda easy :p

and it's exactly as san said, he used the rule of horner i think it was to simplify it.
http://www.physics.utah.edu/~detar/less ... node1.html

thats kinda what it does in a nutshell, not really clear tho but just do a lookup of "Rule of Horner" and u'll find buttloads of stuff

Dont fully understand the (x+1) but I figured it out.

x^2 - 4x + 4 = 9

(x - 2)^2 = 9

x - 2 = +-3

x = 5
x = -1

DOH xD

I remember vaguely doing this in grade 9 I think, and i've never had to use it (or almost anything I learned in any of my highschool math classes) since -.-

lets see, this is simple factoring. some people already solved it, but i'll explain it:

Problem:
x^2-4x+4=9

set one side equal to 0:
x^2-4x-5=0

factor that equation into 2 binomials:
(x-5)(x+1)=0

solve for each x and thus giving:

x=+5
x=-1

Aiyas has the right answers but didn't explain in detail, but I covered that

ever bother to look at my post

Yup san already got it right.

But you could arrange it to x^2-4x-5=0, and draw the graph like so...


the answer you are looking for are the x-intercepts

Lulz parabola Standard form xD

i always pronounced parabol para-bola not paRAbolA