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Guest Stefkov
Posted

Im no good with factorising

(x²+10x+6)

if anyone would be so kind as to work it out.

Posted
How the fuck do I work out percentage increase. Ive tried every sum. £175000 to £215000 thanks

We are starting with 175000, so this is 100%. So lets work out 1%, by dividing 175000 by 100. (= 1750) Now, we need to know the number of "percents" in 215000. We know that if we divide it by this number, we will get 1%.

 

Thus:

 

1750 = 215000/x (where x is the number of "percents" in 215)

 

Rearrange for x:

 

x = 215000/1750

x = 122.9 (1dp)

 

So 215 is 122.9 percent of 175, to one decimal place.

 

Thus the percentage increase from 175000 to 215000 is 22.9% (1dp)

 

In fact, this is the same as the percentage increase from 175 to 215, so if you are sure of this you can remove the zeroes to make calculations easier.

 

Im no good with factorising

(x²+10x+6)

if anyone would be so kind as to work it out.

You must have written this down wrong- the equation doesn't factorise.

Posted
Im no good with factorising

(x²+10x+6)

if anyone would be so kind as to work it out.

 

since it has 1x² it can be worked out by getting a number that multiplys to make 6 in your case and adds to make 10.

 

meh i didnt read the end of the last post. oh well thats how you do it

Guest Stefkov
Posted

You know I get the words wrong aswell.

What is it where it goes to

(x-?)(x-?)

I'm so gonna fail...

 

If it cant be done then I definietely failing this mini test tommorow.

Posted
You know I get the words wrong aswell.

What is it where it goes to

(x-?)(x-?)

I'm so gonna fail...

 

If it cant be done then I definietely failing this mini test tommorow.

Yep, if you want those question marks to be integers, then that question can't be done. You can still solve the equation though, by using the formula- it does have real solutions.

Guest Stefkov
Posted

THe teacher gave us the mark sheet aswell so we could check the answers and theres only one answer in the box, but usually thats at the end, but it has M1, A1, A1. So I thought there was more. If it cant be done then I was wrong about there being more to the answer.

Posted

If someone takes a bead without looking and puts it back 200 times and the results are

 

yellow = 48

 

blue = 64

 

green = 88

 

is the probability of me pulling out a green and blue bead 0.76? as in 64 + 88/ 200.

 

the quadratic formula is x = ((-b +or- (b²-4ac))2a

with two products hence +or-

Posted
THe teacher gave us the mark sheet aswell so we could check the answers and theres only one answer in the box, but usually thats at the end, but it has M1, A1, A1. So I thought there was more. If it cant be done then I was wrong about there being more to the answer.

What was the original question? It can't expect you to do something that it hasn't told you to do.

If someone takes a bead without looking and puts it back 200 times and the results are

 

yellow = 48

 

blue = 64

 

green = 88

 

is the probability of me pulling out a green and blue bead 0.76? as in 64 + 88/ 200.

First, you must make an assumption about the probabilities of taking a bead. If you are assuming that these probabilities are distributed exactly as the data suggests, and that the probabilities are independent (assuming that taking out beads does not affect the number of beads in the bag), then the probabilities will be as follows:

 

Probability(yellow) = Pr(yellow) 48/200 = 0.24

Pr(blue) = 64/200 = 0.32

Pr(green) = 88/200 = 0.44

 

If this is the case, then the probability of drawing out a green bead, followed by drawing out a blue bead is 0.32*0.44 = 0.1408

 

Note that I'm not 100% certain about this.

the quadratic formula is x = ((-b +or- (b²-4ac))2a

with two products hence +or-

Correction: x = ((-b +or- (b²-4ac))/2a

Posted

Ok Chucks question:

 

This could be interpretated so many ways its silly, so:

 

Probability of pulling out a green bead and then a blue bead (replacing the bead each time) = P(G then B) = 5632/40000 = 88/625 = 0.1408

 

Probability of pulling out a green and blue bead in any order (and replacing each time)= P(G then b) + then G) = 0.2816

 

Probability of pulling out a green then a blue bead (not replacing) = 88/200 * 64/199 = 5632/39800 = 704/4975 = 0.1415...

 

and so on.

 

 

@ Supergrunch, you've made one of those silly errors again:

 

quadratic formula:

 

x = ( -b +or- squareroot( b^2 - 4ac) ) / 2a

 

theres a squareroot there, hence allowing complex roots. unless of course the square root symbol isnt showing for me (entirely possible). my apologies if so.

Posted
@ Supergrunch, you've made one of those silly errors again:

 

quadratic formula:

 

x = ( -b +or- squareroot( b^2 - 4ac) ) / 2a

 

theres a squareroot there, hence allowing complex roots. unless of course the square root symbol isnt showing for me (entirely possible). my apologies if so.

Good point. I wish the maths notation on this forum was better, so that we wouldn't need to spend ages analysing and manipulating expressions. Of course, I could do my hints/solutions in open office math, but I can't really be bothered.

 

By the way Chris, did you do FP3? I found an unstarred question (they star hard ones) in my textbook saying:

 

Show that the Lorentz group is a group, and prove that it is Abelian.

 

Obviously they explained what the Lorentz group was, but even so...

Posted
I wrote it a million times i mustav got fed up with the divide

Yeah, we all make mistakes, like I just did. It's best to correct them though, in case someone who doesn't know it already uses an incorrect formula.

Posted
We are starting with 175000, so this is 100%. So lets work out 1%, by dividing 175000 by 100. (= 1750) Now, we need to know the number of "percents" in 215000. We know that if we divide it by this number, we will get 1%.

 

Thus:

 

1750 = 215000/x (where x is the number of "percents" in 215)

 

Rearrange for x:

 

x = 215000/1750

x = 122.9 (1dp)

 

So 215 is 122.9 percent of 175, to one decimal place.

 

Thus the percentage increase from 175000 to 215000 is 22.9% (1dp)

 

In fact, this is the same as the percentage increase from 175 to 215, so if you are sure of this you can remove the zeroes to make calculations easier.

 

There is a quicker and easier way to do this one. Just find the difference between the orginal number and the increase, i.e 215000-175000 = 40000. Then work out what percentage this is of 175000.

 

40000/175000 x100 = 22.9%

 

Both are right, i just thought this one might be easier to understand for future use.

Posted
Sorry dude, sounds too much like pure maths to me. None of my maths books have it in either. I've done very little group theory.

Don't worry, someone (not me) managed to do it. I just thought you might know about it because the Lorentz group is something to do with physics.

There is a quicker and easier way to do this one. Just find the difference between the orginal number and the increase, i.e 215000-175000 = 40000. Then work out what percentage this is of 175000.

 

40000/175000 x100 = 22.9%

 

Both are right, i just thought this one might be easier to understand for future use.

Yeah, that's much better. I just work out methods for these sort of questions from scratch, so some of them (like the one I had for doing this) are probably a bit cronky.

Posted
I lol at how no-one attempted my question XD (which I posted out of interest)

 

Guess there is no budding lawyers on R-E

I answer maths questions because you can give a definite answer, and explain how do it as well.

 

But feel free to give me biology or chemistry questions as well. It is, after all, these subjects that I'm going on to do at university.

Posted

Not strictly related to you doing my homework, but as a lot of Maths people occupy this thread, I thought they might be interested.

 

Anyway, a few days ago I went to a higher education day at Reading univesity in which poeple from all different unis ome down and give talks about different courses etc.

 

The law talk I wanted to go to was cancelled, so i went to the one on being a teacher. The talk lasted 20mins and at the end there was time for questions from students, and one person asked what she'd need to do to be a Maths teacher, the response was "a D at A-Level maths" as "this country is way way short on Maths teachers, so the government and schools are told to take anyone on offer even if they only have the minutest qualifications"

 

I find that incredulous, and I feel sorry for the future maths students who are going to be taught by any old fool who just got a D in Maths at A-Level.

Posted
I could teach most people to get better than a D at maths A level. And the people getting these grades are supposed to be teaching us?

 

Could you teach me how to get an A* at GCSE

Posted

Heya,

I was just wondering if any of you know anything about GSCE Geography. I'm doing my coursework, and I was looking for some pointers.

 

It's on deforestation in the Amazon Rainforest, and I have to write about the various Economic, Social and Environmental effects, and disadvantages and positives of all. Also the different ways of how the Rainforest is being used. I need to use graphs, diagrams and all those sorts of things to express these, and I'm really confused as to where to start.

 

And if anyone could explain the Nutrient Cycle, that would be great!


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