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how do I determine the mass of :3.01 x 10^23
You have no units so you can't.

MelodyOct 31, 2013

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Already answered this for Howdy.

MelodyOct 31, 2013

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tan(x/2)=sin(x/2)

sin(x/2) / cos(x/2) = sin(x/2) / 1

cos (x/2) = 1

x/2 = 0, 2pi, 4pi,6pi, .....

x= 0, 4pi, 8pi, 12pi,

so x = 4n*pi radians where n is any integer

you can do the degrees yourself.

MelodyOct 31, 2013

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A mixture of 12% disinfectant solution is to be made from 10% and 17% disinfectant solution. how much of each solution should be used if 14 gallons of the 12% solution are needed?

I don't think the question is quite complete.

I will assume for starters that you have lots of the 17% solution and you can make it all up from that.

There is a really simple formula for this

Amount of strong concentrate needed = concentration wanted / concentration availble * amount that you want to make up

Amount of strong concentrate needed = 12% / 17% * 14gallons (the percent signs can just be cancelled out)
= 12/17*14
= 9.88 g (to 2 dec places)
Then you will have to add (14-9.88) 4.12 gallons of water.

If you use the 10% mixture you will have to add some of the 17% mixture as well or it won't be strong enough.

MelodyOct 31, 2013

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http://www.mymathforum.com/viewtopic.php?f=8&t=43887

And the proofs just keep coming

This one uses a geometric progression to prove that 0.9repeater = 1

MelodyOct 31, 2013

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its the same as addition. You make it 5*3C-6*5 so 15c-30

GuestOct 31, 2013

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GuestOct 31, 2013

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MIAA:
how do I determine the mass of :3.01 x 10^23

PLEASSEE ? ANYONE ?

GuestOct 31, 2013

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I hav no idea , maybe google will help or this website
www.askmathquestions.com

GuestOct 31, 2013

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What I love about physics is the impact of words.
Like 'net'.
I looked at Melody's answer earlier and thought 'Yep', add gravity to the thrust.
Then the word 'net' poked me in the ear.
maybe the gross force is 19.8N and the net force is only the thrust.
That makes it 10N
Melody might well be right!
Cheers, Mark

GuestOct 31, 2013

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Another mistake.....
divide both sides by 2.5!
That's it I'm outta here

GuestOct 31, 2013

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Oops.....subtract 27!!

GuestOct 31, 2013

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Hello world once more. After midnight in Adelaide Australia.....Bed time.
3y=-1/2x+2 given. And y=-x+9 given
Lets find x.
Substitute that 'y' for (-x+9)
Get...3(-x+9) = -1/2x +2.......slightly messy but so is my kitchen at the moment......
Expand brackets.
-3x+27 = -1/2x+2. Oddball.
Shuffle things around more........
-2.5x = -25.........don't be thrown off by the half x. Move it over like normal. Add the half to both sides. Subtract 25 from both sides.
divide both sides by 3.5.
x=10
Yeeha again!
Just finished dinner with a pure maths PhD student, history PhD student, philosophy PhD student, and a poor medical student. All four on scholarships. I'm just an old engineer feeling rather feeble in such hallowed company. Cheers, Mark

GuestOct 31, 2013

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Hello dear world.....
3x+2y=18...given and y=6x-6 given
Lets find what x is. Looks pretty easy peasy.
Substitute that 'y' for 6x -6
Get....3x + 2(6X-6) =18
Lets expand the brackets......
Get 3x + 12x-12 = 18
Add 12 to both sides........
3x +12x = 30
Combine x's
15x=30
Looks like x is twoooooooo
yeeeha!

GuestOct 31, 2013

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You launch a model rocket up into the sky. Right after launch the rocket is accelerating upwards at 10m/s^2. What is the magnitude of the net force in Newtons on the rocket if the rocket has a mass of 0.1 kg?

I am going to let gravity be 9.8m/s squared.

I think force = 0.1 * (19.8) N = 1.98N

(I am not 100% sure)

MelodyOct 31, 2013

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2=sec(x)

2/1 = 1/cosx

1/2 = cos x

x = 60 degrees or pi/3 radians

MelodyOct 31, 2013

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find the area of a quadrant of a circle whose circumference is 22cm.

First you have to find the radius using C=2*pi*r

Then the area will just be one quarter of pi*r*r

MelodyOct 31, 2013

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What is the least common multiple of 3,4,7

since they have no common factors it will just be 3*4*7

MelodyOct 31, 2013

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what is 3/4-9 = -9 + 3/4 =

start at -9 on a number line and go 3/4 in a positeve direction
hint: It will be between -8 and -9

MelodyOct 31, 2013

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5/8 divided by 1/12

= 5/8 * 12/1

= (5*12) / (8*1)

you can finish it

MelodyOct 31, 2013

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If x=gh what is h+gx(945+231)gx=h

This is a weird question.
h+gx(945+231)gx=h
subtract h from both sides and you get
gx(945+231)gx=0

rearrange
gxgx*1176 = 0

divide both sides by 1176

ggxx = 0
either g=0 or x=0 or they both equal 0

But x=gh
so if g=0 then x=0
but if x=0 either g=0 or h=0 or g and h both =0

MelodyOct 31, 2013

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6+(-6)
=6+-6
If 2 signs(+ or -) are so close together that you can put a circle around them with nothing else in the circle then, if the signs are the same replace with a + and if the signs are differen replce with a -.

You can finish it.

MelodyOct 31, 2013

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20x+7+(-8x)

20x+7+-8x

20x+7-8x

20x-8x+7

can you finish it?

MelodyOct 31, 2013

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5.5cm

just draw the circles like a flat donut.

the radius of the little one is 3cm and the big one is 8cm. This means that there is 5cm between the 2 circles.

If P is equistant from the two cirles it must be 2.5cm from each.

so it will be 3+2.5 = 5.5cm from the centre.

You need to draw the picture to see what I am talking about.

MelodyOct 31, 2013

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what is the antiderivaive of (2t*tan t/2) * sec^2 *t/2 dt from -pi/2 to pi/2

The blue * does not belong there
also I am wondering if this should be

what is the antiderivaive of

2t * tan( t ²/2) * sec ²(t ²/2)) from -pi/2 to pi/2 with respect to t

MelodyOct 31, 2013

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