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Karimazer1

Guest

Please help - Simple Simple Division...I can't do it!

Please help me, this is awful.

I can't calculate

(4p+1/2p) +( 2p+7/(p+1)) = 6.

I want to find 'p'...this is like, grade 7 math?

Because the denominators are different (2p and (p+1)), I don't know what to do, if they were both 2p, I would eliminate them on the LHS and multiply the 6 by 2p...but this isn't the case.

Please can someone wakl me through this, this shouldn't be an issue, the question is hard enough without me being awful at such an early stage! Thank you!!

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help - Simple Simple Division...I can't do it!

hi Karimazer1

I think you are asking for the solution to

If that's correct watch this post as I'll edit it to include the solution.

If it's not post back quickly so I don't waste my time on the wrong question. 

You are right about multiplying by 'p'.  Just extend that idea and multiply by the common denominator.

Cancel the common factors on the left hand side; that gets rid of those nasty fractions.

I get p = 1,882782... or -0.13278...

p = 1 would mean

I'll just use a calculator to check my answers.

My values both give 6 as required. 

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

That is exactly what I'm after, I apologize for still not knowing how to use latex.

Thank you Bob, I eagerly await your response.

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

Thank you Bob, I just tried your method! I expanded and cancelled etc, I got an answer of p=1...

Is that what you got too? Thank you SO much!

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help - Simple Simple Division...I can't do it!

No it isn't.

Watch post 2

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help - Simple Simple Division...I can't do it!

Post 2 complete.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

Thank you!

Ok, I see where I went wrong!

I have got to 4p^2 - 7p - 1 = 0 now .

How do I solve this?

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Please help - Simple Simple Division...I can't do it!

Hi

You should use the formula for the roots of a quadratic equation.

Last edited by anonimnystefy (2012-04-15 06:57:25)

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“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

The reason I'm confused is, we aren't allowed to use calculators.

p is positive, and the answer shows that the equation I asked, is correct..then it just simply says, solve for P.

It should be positive, and should be derivable without a calculator...so I don't really know what to do.

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Please help - Simple Simple Division...I can't do it!

Hi

Use this link:Quadratic formula

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Please help - Simple Simple Division...I can't do it!

Hi Karimazer1;

The quadratic formula is a hand method. It has been suggested to you in post #8.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

I did try it

but whilsdt trying it it gives 7 +/- root of 65...

how can I calculate the root of 65 by hand? without a calculator?

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Please help - Simple Simple Division...I can't do it!

Why not leave it in that form?

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help - Simple Simple Division...I can't do it!

The reason I'm confused is, we aren't allowed to use calculators.

p is positive, and the answer shows that the equation I asked, is correct..then it just simply says, solve for P.

It should be positive, and should be derivable without a calculator...so I don't really know what to do.

Something funny is going on here.

Quadratics that require non - integer square roots don't get set on non calculator questions.  So

(i) you write the answer like this:

or

(ii) that wasn't quite the right question.  Please check it again.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

Thank you BOTH so much for sticking with this.

In the past paper, the equation is completely correct that I posted, I mean, the answers are given (up to that equation, which is considered the hard bit).

The reason we can't leave it in the form posted ^^ is because we then use that p value to finish off the question, by simply putting it back into the original formula to 'show' something else.

This is why it's very confusing for me, because it is a non-calculator question, and everything above is correct.

I don't know.

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Please help - Simple Simple Division...I can't do it!

Hi

Well you can leave it in that form and then simply put it back anywhere you want,and it will even give you more precise results than using a numerical value.

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help - Simple Simple Division...I can't do it!

hi Karimazer1

That may make sense now.  Please post the other bit of the question, then I can show you how to do that even without a calculator.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

Thank you both, again, really appreciated.

So, we must put this 'p', which the whole question is aimed at giving, into:

(4p+1)/2p
(4p+1)/2
(2p+7)/p+1 and
(2p+7)/p+1

The whole question is to derive those 4 things. Then to get p. The 'wrap up' is to substitute back and give those 4 values.

I have absolutely no idea how one could find these by having (7+root 65)/8 (the positive solution is correct, since we're given p is larger than 0 in the question).

I really look forward to your replies on this. Thank you so much.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help - Simple Simple Division...I can't do it!

hi Karimazer1

(4p+1)/2p
(4p+1)/2
(2p+7)/p+1 and
(2p+7)/p+1

??  The third and fourth are the same.  And, apart from calculating these, what.

I'll show you what you can do without a calculator and then you can decide if that's what is wanted.

and

Now I'm not sure what to do now except to demonstrate the following:

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

As much as I appreciate your efforts, please don't waste that much time on me again.

I don't understand anything you've written, why you can just multiply things by other numbers, how some of the numbers get there, etc.

Thx anyway, please stop replying to this thread.

All the best.

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Please help - Simple Simple Division...I can't do it!

Hi

I think that if you have the opportunity to be helped,you should take it. Now tell me what don't you understand?

Last edited by anonimnystefy (2012-04-15 11:41:37)

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“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

It has been confirmed by my teacher that I have to leave it in the form above so it can be done without calculators.

I don't understand ALL of it. As I said, I don't know why, or how I would just think to multiply the whole thing by 8/8...I mean, in what universe would I think to do that? Why does it work? Why would it work?

I don't understand all of it, the maths might be correct but it means nothing without a logical explanation.

All the best.

Karimazer1

Guest

Re: Please help - Simple Simple Division...I can't do it!

hi Karimazer1

(4p+1)/2p
(4p+1)/2
(2p+7)/p+1 and
(2p+7)/p+1

??  The third and fourth are the same.  And, apart from calculating these, what.

I'll show you what you can do without a calculator and then you can decide if that's what is wanted.

and

Now I'm not sure what to do now except to demonstrate the following:

Bob

Administrator

Registered: 2010-06-20

Posts: 10,649

Re: Please help - Simple Simple Division...I can't do it!

hi

Why did I decide to multiply by 8/8  ?

It's a standard trick I use when I've got fractions within fractions.  8 is the common denominator and if you times top and bottom by 8 you don't change the value of the fraction;  just make it simpler.

Then I divided top and bottom by 2 to simplify a bit more.

An expression with root 65 in is called a surd.  The next step is to 'rationalise the surd'.  That is to say, by multiplying by a certain expression (again top and bottom) the square root in the denominator becomes a whole number (strictly a rational number, but in this case it's the same thing).

Here's some simpler examples of these two steps.

The common denominator is 27 so I'll multiply by it.

So that gets me to a simpler fraction.

2nd example.

Here what I'd like to do is get rid of the root 2 in the denominator.  You can always achieve this by multiplying top and bottom by the denominator with its sign switched. ie.

In your problem, this trick did make the expression a lot simpler.  (It doesn't always!)

Now look what happens to the denominator:

See how the roots cancel out on the denominator?  And I'm left with an easy number instead.

That choice of multiplier always does that.

So the original expression becomes

Please don't waste that much time on me again.

I do this because I enjoy it, so don't worry about how much time.

Sometimes it takes several posts before the poster and I have a meeting of minds.  Some threads have gone on for pages and pages.

So, by all means post back, and I'll try to help some more. 

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob