Would i be right in saying that

1/3(x+2)^2-12 = 2/3x^2+2x-12 ?

[Edited on 18/11/06 by Gav]

do you mean:

(1 / (3(x+2))) squared

or

(1/3 (x+2)) squared?

first is equal to 1/(3x+6) squared which surely is 1/(9x^2+36) edit, actually 1/(9x^2+36x+36)

second is (x^2+2x+4)/9

unless ive forgotten how to square fractions.

thats obviously ignoring the -12, which is the same on both sides.

[Edited on 18/11/06 by JoelP]

[Edited on 18/11/06 by JoelP]

Don't think so.
Any way you could write out what you mean and show it on here? It would be much easier to understand that way.

[Edited on 18/11/06 by DIY Si]

What the?

lost me big time!

ok i need to get 1third times (x+2) squared - 12 into a quadratic ie ax squared + bx + c

[Edited on 18/11/06 by Gav]

The straight answer is no (i think):

Thought as:
(x+2) squared multiplied by 1/3 and then subracting 12 gives:

(1/3 * (x^2 + 4x + 4)) - 12

= (1/3 * (x^2 + 4x + 4)) - 36/3

= 1/3 * (x^2 + 4x - 32).....

any help??

easiest way to show it, without lots of fractions in it is 1/3 * (x^2 + 4x - 32 )

1/3 * (x+2)^2 - 12

1/3 * (x^2+4x+4) - 12


1/3x^2 + 4/3x + (4/3 -12)


1/3 x^2 + 4x/3 - 32/3

3 answers and we all agree!

[Edited on 18/11/06 by JoelP]

Or as an open thing 1/3x^2 + 4/3x -32/3

i edited mine due to the confusion over 4/3x and 4x/3, technically the same thing but it can be read wrong!

just eating my tea, ill give a smartie point to the correct answer, ill work it if its right for my parabola after tea

True, that's why I put it the first way first. Leaves less to the imagination.

If you can post a graph of the parabola with a few important point son it, we can probably get you the answer before you've finished your tea.

Is the correct answer 2 hats?

parabola:


Description

ok the problem i have is that when i converted the equation 1/3(x+2)^2 - 12 to a quadratic i found the to x-intercepts to be 4.3 and -9.7 which is close but obvisouly not right!

edit: yes im trying to prove the x-intercepts are correct.

[Edited on 18/11/06 by Gav]

too long ago without a trip to the attic, but my attempt

x^2+4x-6 ..............??????

car building and maths questions...wot a site

does it bottom out at -12, -2?

The vertex is correct at -2, -12

Just found another example which is correct:
-2(x-1)^2 + 1 = -2x^2 + 4x -1

its factorising i suck at, especially when fractions are involved :S

The equation is, I think, 1/3 x^2 + 4/3 x - 32/3
Or, 1/3 * ((x +8)(x -4))

[Edited on 18/11/06 by DIY Si]

You were close but not quite right

Answer is 1/3x^2 + 4/3x - 12

which gives -8.234 and 4.324 which if you look at the parabola looks just about right for the x-intercepts

can't be -12, or it would cross the y axis at -12! Instead it crosses at -10 2/3.
Besides even if i am wrong (and it's been known to happen), it's the first bit of algebra I've done since A levels, which was 4 years ago.

[Edited on 18/11/06 by DIY Si]

Actually you are right

Answer is 1/3x^2 + 4/3x - 32/3 which gives -8, 4

Which was first seen on the first page by joel

Also why I put it in the form above, as it makes finding the crosses easy, as you just have to make either bracket equal 0 to find the two, ie -8 for the first bracket and 4 for the second.

[Edited on 18/11/06 by DIY Si]

a well at least ill sleep well tonight after ive finished this bottle or brandy to cure the headache this gave me

[Edited on 18/11/06 by Gav]

Forgot to say, thanks for the help chaps

Headache from that???? Don't ever be tempted to do Further Maths as a a level then. That's considered basic! Not that I can remember any of it though.

Only reason im donig this course is becuase i thought it would be interesting to get some maths behind me in the OU degree im doing(Computer Sciences) before that i only did GCSE level and got a D at that, oddly enough though got a B in physics!

Its hard unless you have someone who can help you and talk you though it, the OU tutors arent really that helpfull they just tell you to re-read section x page y etc, so considering im learning this all from a book i dont think im doing to badly!

In which case you're doing well. I was fortunate enough to be in a class of just 3! Near enough 1 on 1 teaching. It does help that maths and physics were my best two subjects. I even ended up teaching half my physics set though. I am however, about as arty/ creative as a house brick! Swings and roundabouts I think.
Ps, if you ever need help, just ask on here, or U2U me. I should be able to help with most stuff you're likely to need.

[Edited on 18/11/06 by DIY Si]

strangley enough i was looking at ou courses yesterday.

which ou maths course are you doing?

4x (x/4+1)=32

i always get stuck at this point. When theres two x's mentioned, how do you resolve it for the two y=0 points without resorting to trial and error?!