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Well, let's write out an equation for this word problem. He sold one of them at cost price, (N) and the other 3 at 40% more than cost price [ 3(n+.40n) ] and the total was 260.

N+3(N+.40N)= 260

N+3N+1.2N=260

5.2N=260

N = 50

The original cost of each handbag was $50!

-5/11 is a rational number.

In short, a rational number is is a number that can be represented as a fraction like 3/4 or 8. (Remember, we could write 8 as 8/1)

An irrational number is something that cannot be represented as a fraction, like pi = 3.141592… or √2 = 1.414213…

The numbers will just keep going forever with no repetitive patttern, so they are irrational.

Alan you're the best! That answers my questions, as i've forgotten so much about maths!

I bought one of those Algebra for dummies books to go right back to basics again and do the remedial work i need.

Really i only need to know enough to be able to do the math for circuits like the ones in the book we have by

Neil Storey and stuff related to that.

I got back into doing this because i'm a guitar player and love working on amps replacing capacitors and

resistors and the likes and stuff so am always studying amp schematics. Most of those things can

be worked out by using Ohm's Law which is pretty simple. But when you get to more advanced

problems/circuits like

we're discussing then that's where my lack of maths knowledge really gets me!

I have two amp textbooks by a guy called Merlin Blencowe. He has a Preamp one and a Power Amp one. In

those he also has quite a lot of maths in places. Some very easy involving Ohm's law and it's variants. But

others quite complex. So that has been another reason for me to try to learn more about all this. It becomes

very interesting to me after a while.

You'd understand everything that Merlin writes in the books regarding equations. But some of it i struggle

with. I learnt a lot of good stuff from chapter 2 in Neil Storey's book about phase angles and sine waves that

helped me deciphering stuff from Merlin's books 

Thanks very much Alan this has helped me a lot.

 Gary

As a rough approximation the temperature will fall exponentially.  That is the temperature as a function of time is given by:

T(t) = Ta+(T0-Ta)*e^-k*t

T(t) is the temperature at time t

T0 is the temperature at time zero (185°F)

Ta is the ambient temperature (51°F)

k is a constant we can find from knowing that the temperature at t=30mins is 150°F

150 = 51 + (185-51)*e^-k*30

ln((150-51)/(185-51)) = ln(e^-k*30)

ln(99/134)=-k*30

k = -ln(99/134)/30  ≈ 0.01 per minute.

So the temperature after 45 minutes is:

T(45) = 51 + 134*e^-0.01*45 ≈  136.4°F

Time for turkey to cool to 100°F is given by:

100 = 51 + 134*e^-0.01*t

ln(49/134) = -0.01*t

t = -100*ln(49/134) ≈ 100.6 minutes

5 consecutive numbers can be represented by: N, N+1, N+2, N+3, N+4.

So we have:

(N) + (N+1) + (N+2) + (N+3) + (N+4) = 1/2(N+2)*10

5N + 1 + 2 + 3 + 4 = (1/2N +1)*10

5N + 10 = 5N + 10

5N = 5N

N = N

I believe this is saying that N could be any number, because we couldn't solve for it.

Let's check this by putting some random numbers for N in to the equation:

N = 10

(N) + (N+1) + (N+2) + (N+3) + (N+4) = 1/2(N+2)*10

((10)) + ((10)+1) + ((10)+2) + ((10)+3) + ((10)+4) = 1/2((10)+2)*10

10 + 11 + 12 + 13 + 14 = 1/2(12)*10

60 = 6*10

60 = 60

N = -7

(N) + (N+1) + (N+2) + (N+3) + (N+4) = 1/2(N+2)*10

((-7)) + ((-7)+1) + ((-7)+2) + ((-7)+3) + ((-7)+4) = 1/2((-7)+2)*10

(-7) + (-6) + (-5) + (-4) + (-3) = 1/2(-5)*10

-25 = (-5/2)*10

-25 = -50/2

-25 = -25

oh!im sorry i thought it was a joke!Yes maybe ND is right, becoz of ur caps lock maybe u cant login!Try once again!

Is your caps lock on?

That one stoped me from logging in once, since passwords are case-sensitive.

I agree with anonymous, it is the same thing

If you think about it, 0.25 is the same thing as 1/4.

So this is saying that multiplying by 1/4 is the same thing as dividing by 4.

This is true. Remember when you want to divide by a number, you can multiply by it's reciprocal. So for example

40 ÷ 4 = 10

40 * 1/4 = 40/4 = 10

Just to prove the point, take some random numbers and multiply them by 0.25, then take that same number and divide it by 4.

-----------

4 ÷ 4 = 1

4*1/4 = 4/4 = 1

------------

10 ÷ 4 = 2.5

10 *1/4 = 10/4 = 2.5

-----------

There you go. It works.

In the first rearrangement of the first equation: where are you getting the 5 from? 

(50-V2)/10 + (V3-V2)/20 + (0-V2)/15 = 0 This can be written as:

50/10 - V2/10 +V3/20 - V2/20 +0/15 - V2/15 = 0

The first term above is just 50/10 = 5; so that's where the 5 comes from.

Same with the bit where  we have 5 - 13/60 where is the 13/60 coming from?

Collect all the terms involving V2:  -V2/10 - V2/20 - V2/15  Factor out -V2 to get:

-V2*(1/10 + 1/20 + 1/15)  Collect the fractions together as a single fraction.  To do this we need to find a common multiple of 10, 20 and 15.  Any multiple will do, but often life is easier if we use the lowest common multiple.  In this case that is 60, so we can express the individual fractions as:

1/10 = 6/60

1/20 = 3/60

1/15 = 4/60

So now the sum can be written as 6/60 + 3/60 + 4/60, and because they are all over the same number we can write  6/60 + 3/60 + 4/60 = (6 + 3 + 4)/60 = 13/60.

Hope that helps!

yes that is correct to my understanding...

sorry !Thats only was the real solution!

OHH!Thats all so sad!Poor Zegroes got no where else to hide his face behind!

Becoz u have no registerd account!

Hope i answered u properly!

yes Quazars you explained very well!

So Anonymous we'd solve this like this:

1/3 ÷ 2  ( so now we'll reciprocate this)

=1/3 x 1/2  (out here we have reciprocated as well as changed the division sign to multiplication sign)

=1/6  ANSWER

I hope uve understood by now and if not then pls be free to ask!

I hope this helps!

good ! Thats what i was trying to tell you!to try it yourself!And see the result now , u've learnt it very nicely!Thumbs up from me for ur answer!

x-126*19=46

im going to try the inverse (46x19)+126=1000

(1000-126)*19=46

yes i got it

Thank You Melody!and you too!

Okay, enjoy your day Rosala.  

thank you Melody ! That just gave me a relief!

I actually was just saying sorry for my mistake!and saying sorry will help me not to repeat it!

And i dont mind now being called a kid (oh , i hope Zegroes doesnt read this, well i can use some magical powers to appear this as invisible to him) ! 

And have a happy Monday Melody!I am going to have mine this time becoz i have no test on Monday actually i had one of German but it shifted to Tuesday!

So enjoy!

Thanks you Ninja. 

It is the same as acos

inverse cos and arc cos are the same thing.

so just press 2nd then acos

It is much the same on almost all calculators.  

That is okay Rosala,

I didn't mean to be too cranky.  It was only intended as a reminder, that is all.

You are all really good kids.  (I hope you don't mind being called a kid.)  And sometimes it is easy to get carried away.

Please do not feel bad or be too appologetic, it is not warranted.

Stay happy,

Melody.

I'm really sorry Melody i shouldnt have had fun on that serious post!i had almost forgotten that u told us not to have fun on serious posts!I'm sorry my mistake will not be repeated!i should have been matured enough to not to start a fun on that post and post funny arguing answers!I'm sorry my mistake will not be repeated!