Turn on thread page Beta
 You are Here: Home >< Maths

Any1 brainy out there? help pls! watch

1. ok so I've got this math question about algebra- completing the square...
i dont hav a clue how to answer it... help please?
2. (Original post by #animal-lover)
ok so I've got this math question about algebra- completing the square...
i dont hav a clue how to answer it... help please?

here is the question....
3. (Original post by #animal-lover)

here is the question....
ok so the coefficient of x^2 is 1, meaning that we can use the general formula for completeting the square:

x^2 + ax + b = (x+a/2)^2 -(a/2)^2 + b

Then once u have that formula rearranged to the general formula, u can make it equal to 0 and solve it.
4. wen i saw u were looking for anyone brainy, i was thinking yep defo me, but bruv wat the f is that, is it some made up question or wat?

In other words cant help u b
And brainy isnt part of my resume or personality traits
5. (Original post by AKA2234)
bruv wat the f is that, is it some made up question or wat?
...it's the quadratic formula, goddammit!
6. dude i knew that, but i was done with maths last year, literally messed up my brain, forgot everything about it
7. (Original post by brownguytorule)
ok so the coefficient of x^2 is 1, meaning that we can use the general formula for completeting the square:

x^2 + ax + b = (x+a/2)^2 -(a/2)^2 + b

Then once u have that formula rearranged to the general formula, u can make it equal to 0 and solve it.
soo your saying x^2 = 1??
so is it gonna be (x+9)^2 + 4= 0???
8. if you are trying to complete the square for

y = x2 + 18x + 4

you can start off by dividing the 18 by 2 to get 9...

y = ( x + 9 )2 + ....

now think about 92 which is 81.

how can you reduce 81 down to 4 ?

minus 77....

so put it together

y = ( x + 9 )2 - 77

after that you have to solve

( x + 9 )2 - 77 = 0

which you can do yourself.
9. the formula for the quadratic equation is: ax^2+bx+c=0
in your case, a = 1 b = 18 c = 4
the formula for finding x is:
x1 = (-b + sqrt(b^2-4ac) ) / 2a
and
x2 = (-b - sqrt(b^2-4ac) ) / 2a
so the answers for that are:
x1 = (-18 + sqrt(18^2-4*1*4) ) / 2*1 = -9 + sqrt308
and
x2 = (-18 - sqrt(18^2-4*1*4) ) / 2*1 = -9 - sqrt308
cheers
10. (Original post by the bear)
if you are trying to complete the square for

y = x2 + 18x + 4

you can start off by dividing the 18 by 2 to get 9...

y = ( x + 9 )2 + ....

now think about 92 which is 81.

how can you reduce 81 down to 4 ?

minus 77....

so put it together

y = ( x + 9 )2 - 77

after that you have to solve

( x + 9 )2 - 77 = 0

which you can do yourself.
Ok so how abt the question: x2+ 12x + 4 = 0
11. (Original post by #animal-lover)
Ok so how abt the question: x2+ 12x + 4 = 0
12 divided by 2 = ?

?2 = ??

how do you get from ?? down to 4....
12. (Original post by #animal-lover)
Ok so how abt the question: x2+ 12x + 4 = 0
the formula is already given above.

x1 = -6 + 0.5*sqrt128
x2 = -6- 0.5*sqrt128
13. (Original post by the bear)
12 divided by 2 = ?

?2 = ??

how do you get from ?? down to 4....
12 divided by 2 is 6
so 62 = 36
so how do u get from 36 down to 4??
14. (Original post by #animal-lover)
12 divided by 2 is 6
so 62 = 36
so how do u get from 36 down to 4??
okay... what do you do ?
15. x2+ 12x + 4 = 0

x= ....... + √..... or x= ........ - √.......

that is the question on my paper- i have to give a postive and negative answer using that equation....
the ...... is a space that i have to fill in
hmmmmm
16. (Original post by #animal-lover)
x2+ 12x + 4 = 0

x= ....... + √..... or x= ........ - √.......

that is the question on my paper- i have to give a postive and negative answer using that equation....
the ...... is a space that i have to fill in
hmmmmm
x= -6 + √32 or x= -6 - √32
17. its better to google how to solve quadratic equations, mate

Reply
Submit reply
Turn on thread page Beta
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: October 26, 2017
Today on TSR

Oxford Interviews

Find out which colleges are sending invitations

University open days

• University of East Anglia
UEA Mini Open Day Undergraduate
Fri, 23 Nov '18
• Norwich University of the Arts
Undergraduate Open Days Undergraduate
Fri, 23 Nov '18
• Edge Hill University
All Faculties Undergraduate
Sat, 24 Nov '18
Poll
Useful resources

Make your revision easier

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

How to use LaTex

Writing equations the easy way

Study habits of A* students

Top tips from students who have already aced their exams

Create your own Study Planner

Never miss a deadline again

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.