Any Maths people around - need to find where two lines cross

15 replies
Found 18th Feb 2009
Doing my maths homework & have got a problem, I know the question (obviously) & also the answer, but I just cant work out how to get from the question to the answer...

The question is an intergration question but first I need to find where the lines...

y = 2x & y = x ^ 0.5 (thats square root of x but I cant do the sign on here)

Anyway, this is what I did...

2x = x ^ 0.5

2 = x ^ 0.5 / x ^ 1 (thats a division sign by the way if it isnt clear)

2 = x ^ -0.5 (sure when dividing you subtract the powers so I get negative 0.5)

Now I get stuck, I need x on its own & know the answer is x = 0.25 as I have plotted it on a graph on the computer.

So I could just do it from that but its really bugging me & I want to know how I get from....

2 = x ^ -0.5 to 0.25 = x (assuming I have gone about it the correct way)


Any help would be really appreciated as I would like to get it finished, also I am hoping to do a maths degree so I need all the knowlage I can get!

Thanks alot
James

15 Comments

tut tut, kids nowadays....
sigh

Original Poster

Shush :lol: its not cheating or anything, just a bit of extra help haha!

Well x to the minus 0.5 is equal to one over x to the 0.5.
This means you can then re-arrange to give x^0.5 = 1/2
x^0.5 is the same as square rooting, and the square root of 0.25 is 0.5.
Et voila.

It's not cheating at all - I'm a Physics teacher, and as long as my students understand the steps they've been shown, and could apply them in a new situation, then they've learnt something. Which is always useful!

Original Poster

That is brilliant thank you!!!!!! Reps coming your way.

I didnt think to use the reciprical (one over x ^ 0.5) as I thought I would need x on its own rather than back into another fraction.

Makes sense now though, thanks alot!

Original Poster

Muhammadoli;4414976

It's not cheating at all - I'm a Physics teacher, and as long as my … It's not cheating at all - I'm a Physics teacher, and as long as my students understand the steps they've been shown, and could apply them in a new situation, then they've learnt something. Which is always useful!



A physics teacher, keep your eyes peeled for my next lot of homework then haha!

Been enjoying Physics at AS Level, miles harder than GCSE (somehow got 100% in that, only understood it when I started revising for the exam)

Our January Exam went OK, it was about Particles & Quantum Radiation (may have got slightly mixed up) and Electricity.

Currently doing the Mechanics, Waves, & forces at the moment for out June Exam, I am finding the forces really interesting, we are doing things such as SUVAT, moments, torque etc. Quite hard to get your head around alot of it though, struggling with some but going to start going to the Workshops after college as I really want to get an A in it! :thumbsup:

I did maths once....... it was a tuesday, ahhhhh memories.

What a good use of this board, no point in getting stuck on something when, as you found, there are people out there more than willing to help. :thumbsup:

MinstrelMan;4415196

I did maths once....... it was a tuesday, ahhhhh memories.


I'm still wondering which day to choose for mine

snowtiger;4415226

I'm still wondering which day to choose for mine



does it matter? when you're old (and you are) everydays the same :p:w00t:

Original Poster

Shark Girl;4415210

What a good use of this board, no point in getting stuck on something … What a good use of this board, no point in getting stuck on something when, as you found, there are people out there more than willing to help. :thumbsup:



I agree, really helpful, tried phoning some friends but they had given up on this question :thumbsup:

MinstrelMan;4415251

does it matter? when you're old (and you are) everydays the same :p:w00t:


old? ...... OLD!! :w00t: ... ........................ ... spose' not

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cheeky menstrual man :roll:

snowtiger;4415317

old? ...... OLD!! :w00t: ... ........................ ... … old? ...... OLD!! :w00t: ... ........................ ... spose' not :pcheeky menstrual man :roll:



what can I say...... i'm a cheeky lil chappie
:thumbsup:

OMG, am I glad that I left school 19 years ago!!

its quite simply really.

y=2
x=0.5
then when you / x ^ 1 = tree.fiddy
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