Rom

7 Questions
2456 Answers

+9

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+6251

is there any point to answering these anymore?

Does anyone even look at the answers given?

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Rom Mar 3, 2020

+1

1762

9

+6251

latex delimiters

Is there a way of embedding LaTex into posts w/o using the LaTex button and dialogue?

Other boards have $$, [tex][/tex], [math][/math]
read more ..

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Rom Aug 8, 2019

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You know what guarantees I won't look at your problem?

Using the words ASAP, or fast, or now, or anything similar in your title.

You're all quite fortunate to have the group of us here that answer your questions.
read more ..

off-topic

Rom Jan 4, 2019

+2

1303

0

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sub forums

It might be nice to have a few sub forums so we know better how to address given problems.

For example I suspect we sometimes use calculus to answer questions posted by people in pre-calculus classes.
read more ..

Rom Nov 27, 2018

+2

1466

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Why do sometimes we get the option to filter out answered questions but sometimes we don't?

Why do sometimes we get the option to filter out answered questions but sometimes we don't?

off-topic

GingerAle ●●●●●●●●

Rom Nov 15, 2018

+26

3062

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I'm concerned that we are just doing people's homework for them. That's no way to encourage people to actually learn the math.

I'm concerned that we are just doing people's homework for them. That's no way to encourage people to actually learn the math.

Thoughts?

CPhill ●●●●●●●●●●●●●●●●●●

Rom Oct 16, 2015

+2

1700

1

+6251

help file?

Is there a help file somewhere on how to use the forum tools to get a decent math output display?
Does this board support LaTex?

Rom Jan 30, 2014

+6251

+1

http://www.wikihow.com/Prepare-Amortization-Schedule-in-Excel

RomFeb 4, 2014

+6251

+1

is that your mommy I hear calling you?

RomFeb 4, 2014

+6251

+1

Quote:
How to use tan-1?

what do you mean how to use it? What does tan ^-1 mean? How to punch it in on the calculator? Why you would ever want to use it? What?

RomFeb 4, 2014

+6251

+1

RomFeb 4, 2014

+6251

+1

you can always remember that

(wavelength)*(frequency) = (speed of wave propagation)

This is valid for all waves.

Radio waves have a propagation speed of the speed of light i.e. c which is about 3x10 ⁸ m/s

so for radio waves

wavelength = c/frequency = 3x10 ⁸/frequency meters

you can plug in the numbers

RomFeb 4, 2014

+6251

+1

I should note that there is a simpler way to solve this.

Since the point on the flange is spinning at the same angular rate as the wheel itself you can just do this

flange linear speed = (distance to flange)/(distance to wheel) * (train speed) = 31/30 * 60 mph = 62 mph

RomFeb 3, 2014

+6251

+1

MissRaevalynn is correct.

Area = base * height so

200 = 12 * height

height = 200/12 = 16.67

RomFeb 3, 2014

+6251

+1

Quote:
a train wheel has a diameter of 30 inches to the rim, which rests on the track. the flange,which keeps the wheel from slipping off the track, projects 1 inch beyond the rim. when the train is traveling 60 mph, what is the linear velocity in mph of a point on the outer edge of the flange?

fun question

Ok there are basically two parts to solving this.

First, given that the train moves forward at 60 mph we have to figure out how fast the wheel is spinning. This is called it's angular frequency and is measured in revolutions/second.

Then given it's angular frequency and the distance to a point on the flange d the linear velocity is

point on flange linear speed = 2*pi*d*(angular frequency)

We have to assume there is no slippage between the wheel and the track.

The wheel makes one circumference for every complete revolution.

In this case this is 2*pi*30 inches = 60 pi inches/revolution

60 mph = 60*5280*12/3600 inches/second = 1056 inches/second

So the wheel has angular velocity of

1056 inches/second / (60 pi inches/revolution) = 88/(5 pi) revolutions/second

Now the flange is 31 inches from the center. So it will have linear velocity of

88/(5 pi) (revolution/second) * 2*pi*31 inches/revolution = 88*2*31/5 = 5456/5

and to put this back into mph we have

5456/5 inches/second * 3600/(12*5280) sec/hr /(inches/mile) = 5456*3600/(5*12*5280) = 62 mph.

RomFeb 3, 2014

+6251

+1

Quote:
what is the answer to 4x-7y=3
x-7y=-15

First you set the two on top of each other so you can visualize them better

4x -7y = 3
x -7y = -15

now since you have -7y in both you can subtract the 2nd equation from the first one to get

(4x - x) + (-7y -(-7y)) = 3 - (-15)

3x = 18

x = 6

and just plug this back into either equation, I'll use the first one

4(6) - 7y = 3

24 - 7y = 3

21 = 7y

y=3

and your solution is thus

x=6, y=3

RomFeb 3, 2014

+6251

0

I'd take it a step further and say that negative number must be enclosed in parentheses when being exponentiated. As you've noted the likelihood for confusion is too great to ever leave it to chance.

RomFeb 3, 2014