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AMBER:
WHAT IS 1022.32 DIVIDED BY 25%

GuestJan 16, 2014

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Another easy way to convert sin to cos (and vice-versa):

sin(x) = 1/3

just look at the fraction: take the denominator squared, minus the numerator squared and take the square root of that whole thing. Divide that by the original denominator and there you have your cosine.

So:

Sqrt(3^2-1^2) / 3

You can do these exact same steps to convert from cos to sin.

GuestJan 16, 2014

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The first answer was right, here is just another way to look at it/ remember it:

SOHCAHTOA
Sin = Opposite / Hypotenuse
Cosine = Adjacent / Hypotenuse
Tangent = Opposite / Adjacent

so if sin(x) = 1/3

then Opposite = 1, and Hypotenuse = 3

Hint: by pythagorean's theorem we know that Hypotenuse ² = Opposite ² + Adjacent ²

You already have Hypotenuse, so just solve for adjacent using the pythag. theorem and plug it into: cos(x) = A/H

GuestJan 16, 2014

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Dear Melody,

Thank you very much for your correction, so I just have to state --> if Q = 500 - 40P + P2, then Q1 = 2P - 40, without P1 = - 1/40 + 1/P right?

Thanks.

GuestJan 16, 2014

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juicesimmons:
If the modulus of elasticity of the beam is 1.5x106 psi and a 200 lb weight is placed at the center, 4 ft from each end, how much would the beam deflect?

I have no idea I suggest that you post this in

physicshelpforum.com

Just a suggestion. You will have to join up first. (No cost)

MelodyJan 16, 2014

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Kat:
So I'm trying to find the PE (potential energy) and this is the equation: (10-kg)(10m/s/s)(25-meters) (I don't like your little strokes) (m/s/s = m/s * 1/s = m/s²)
Am I just supposed to multiply all of that? Is there any sort of conversion going on here? Because, it DOES have to come out in Joules (J)

1Joule = 1 Kg m ² / s ²

(10kg)(10m/s ²)(25meters) = 10*10*25 kg * m/s ² * m

The units will be right so yes, just do the multiplication.

MelodyJan 16, 2014

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guest:
Dear All,

Please help to check my answer for below questions :

===================================================

the demand function of a product is : Q = 500 - 40P + P²

P : price/unit (dollar), and Q : the amount of production.

questions :

a. Determine the elasticity of demand when the price is = 15.
b. If the price is increased by 5%, what will happen to the demand?

my answer :

a. Q = 500 - (40x15) + 15²
= 500 - 600 + 225
= 125

if Q = 500 - 40P + P², then Q₁ = 2P - 40, and P₁ = - 1/40 + 1/P
if Q = 500 - 40P + P², then dQ/dP = 2P - 40, and where did you get P' from?
So I guess Q'=2*15-40=-10

E = dQ/dP x P/Q
= -10 x 15/125
= -1,2 (Do you use commas instead of decimal points?)

b. If the price is increased by 5%, the demand will be decrease to = 1,2 x 5 = 6 (I don't think so)

===========================================================

Thank you very much for the correction..

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

I have never done this before, I just googled it then to see if I could help you.
I think that part a is correct except for the coloured changes/ additions that I did.

Now part b
E = -1.2
I think this means that if price goes up by 1.2%, the demand will go down by 1%
You want to know what will happen to demand if the price goes up by 5%
so let the change in demand be d%
so this is the equation that you have to solve.
1.2% / 1% = 5% / d%

1.2 = 5/d
d = 5/1.2
d = 4.2 (1 dec places)

so if the price increases by 5% I think that the demand will decrease by 4.2%

Like I said, I hadn't even heard these terms before I googled them for you just a moment ago.
But that's what I think.

MelodyJan 16, 2014

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GuestJan 16, 2014

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*
If you like jigsaw puzzles and you want to learn where places are, this is the site for you.

The countries are the pieces of a jigsaw and you can play at different levels of difficulty.
these geography interactive sites are a fantastic way of learning where places are!
Just copy and past this address into your browser.

http://www.yourchildlearns.com/map-puzzles.htm

Please let other people know how you like it.

MelodyJan 16, 2014

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Tim_St:
hi)

Hello Tim, its nice to meet you.
Why don't you add a post to one of the green smiley questions.
Some of them are easy.
I'd love to see you make a proper post.

MelodyJan 16, 2014

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+26

Everything is all up to date now.

Helper today included reinout-g i_luv_math_300, cxz\xc, and a couple of guests.
Thank you, your answers are really apreciated.

I would like to remind everyone that the aim here is to help people learn. If you give an answer without an explanation then not much learning is going to happen.
Therefore please try to explain how you got your answer.

Iwilli28 offered a number question. I think it was intended as a sort of number puzzle. '28 tacked it onto another post.
I reposted it awith the green smilie symbol.
Thankyou Iwlli28 for your contribution.

I know people are getting very busy with school and other activities but could you please make a contribution to the puzzles and continuing posts from time to time, just to keep them rolling.

Thank you everyone
Melody.

MelodyJan 16, 2014

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kpop1015:
Ahhhh thank you. Its for my algebra homework and i was having A LOT of trouble.I still havent fully gotten it but i will^^

Ok, since you got back to me I will try to be more helpful.
Maybe try these, you can do them just with normal factorising. That is how I want you to do them.

1) x ² + 9x = -20

2) x2 -1x - 8 = x

3) 2x ² + 15 = -13x

If you find Q3 difficult i will show you an easy (well, probably easier anyway) way to do it.
If you have problems I will show you how it is done. If you post your work, just copy my equations and insert your working underneath so that it all stays together.

MelodyJan 16, 2014

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Ahhhh thank you. Its for my algebra homework and i was having A LOT of trouble.I still havent fully gotten it but i will^^

kpop1015Jan 16, 2014

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kpop1015:
How do you solve quadratic equations?

By putting all the terms to one side with the other side =0
then by
factorising, or
completing the square method
or by using the quadratic formula.

MelodyJan 16, 2014

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iiiiiii:
Some earthquake waves travel at 5 km/sec. What is the λ of these waves if the earth tremors are 10/s

Zamarronics has done this efficiently and you will probably choose to remember the formula and do it that way.
Thankyou Zamarronics,

I just wanted to show you a different method.
Mine is done all as rates. It can be used on all sorts of rate problems.
I used it heavily when I was teaching nurses drip rates and stuff like that.
I also use it when I convert one countries currency to another because otherwise I get confused about whether I should multiply of divide.
anyway, this is it for this problem. It would normally only be 2 lines but I have extended it with explanation.
I hope you try to understand what i have done.
140116 wavelength.JPG

MelodyJan 16, 2014

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MelodyJan 16, 2014

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braidengreg:
y=m(7)+5

I am sorry but this is not a question.

MelodyJan 16, 2014

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Thank you Zamarronics, I think i have fixed all the places where I spelt your name incorrectly.
------------------------------------------------------------------------------------------------------------------

Now for the divisability checks. What do we have so far?

1) We have Zamarronics's formula,

2) A number is exactly divisable by 10 if it has a zero at the end. (the last digit is zero)

3) A number is exactly divisable by 2 if it is even.

4) If a number is prime then it is only exactly divisable by 1 and itself

5) A number is exactly divisable by 5 if it ends in 0 or 5

6) A number is exactly divisable by 3 if the sum of its digits is exactly divisable by 3.
------------------------------------------------------------------------------------------------------------------------

There are lots more to do but lets look at these ones.
Who can give me a number that is at lease 6 digits that is
divisable by 10, 5, 3 and 2
You are not allowed to use you calculator and i don't want you to do the division.
Just with minimal work, I want you to give a number that fits the description and tell everyone why it fits the description.

There are an infinite number of answers so more than one reply would be excellent.
Please join in.
--------------------------------------------------------------------------------------------------------------------------

I'll start. My number is 387,420
It is divisable by 10 and 5 because it ends in a 0
The last digit, 0, is even, so it is divisable by 2
3+8+7+4+2+0 = 24
and 24 is divisable by 3 (24 divided by 3=8)
Therefore 387,420 is divisable by 3

MelodyJan 16, 2014

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Bills:
solve the equation 7x+1=-2

Start by subtracting 1 from both sides.

MelodyJan 16, 2014

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xPlayinWithFire:
Okay, so I have a 72 in one of my classes, what do i have to get on my final to keep passing the class?

beats me, I need lots more info than that.

MelodyJan 16, 2014

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Now popy

you can line them up underneath each other and add them up yourself.

MelodyJan 16, 2014

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Guest:
If I give you one penny today, two pennies tomorrow, the next day 4, and so on, how may pennies will you have by in one year?

This is the sum of a geometric progression.
the progression is

1,2,4,8,16,
what is a?
what is r?
what is n?
what formula will you use.?
Do the calculation.

which of these steps is causing you a problem?

MelodyJan 16, 2014

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GuestJan 16, 2014

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Guest:
2x+3=7x-2

The first aim is to get all the xs to one side and all the numbers(without xs) to the other side.

you do this by saying, what do I want to get rid of.

It would be good to get rid of the +3, what is the opposite of adding 3, taking 3 away would be a good answer.
but, if you take 3 away from the left hand side, you have to take 3 away from the right hand side as well
so you get
2x+3-3 = 7x-2-3
2x = 7x - 5
next you need to get rid of the 7x from the right hand side, what is the opposite of adding 7x (there is an invisable + in front of the 7) taking it away wouldbe correct.

You see if you can finish it,
Post again if you get stuck.

MelodyJan 16, 2014

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itzmetheguy:
sin x=1/3
find cos x

Draw a right angled triangle
mark the right angle and the x angle
put the 1 and the 3 in the right spots.
work out what the other side is
then
read cos x of the triangle.

MelodyJan 16, 2014

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