Rom

7 Questions
2456 Answers

+9

1202

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+6248

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

1752

9

+6248

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

+6

1793

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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

1293

0

+6248

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

1440

8

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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

3043

18

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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

1684

1

+6248

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

+6248

+1

i'm betting he means it's called the circle.

RomJan 30, 2014

+6248

+1

minus a negative is the same as plus so

22 - (-13) = 22 + 13 = 35

RomJan 30, 2014

+6248

+1

Quote:
5 log (base 7) x - 2 log (base 7) x

since the log bases are the same you can use the properties of logarithms

a log(x) = log(x^a)

log(y) - log(x) = log(y/x)

using both of these you get

log(base 7, (x^5)/(x^2)) = log(base 7, x^3)

RomJan 30, 2014

+6248

+1

http://www.youtube.com/watch?v=p6hcLw4lzTQ

RomJan 30, 2014

+6248

+1

if you can get here you can get to google and type 350/5

RomJan 30, 2014

+6248

+1

Quote:
Okay, so once again I've been having troubles with a couple of questions and need help! They need to be solved using either the steps of TVM (total value of money calculator) or using the equations A=P(1+i)^n. Here are those questions:

1. Barb invests $15,000 for 7 years and it doubles in value. What interest rate, compounded quarterly was the money invested at?

2. How much longer will it take $25,000 to amount to $100,000 if it is invested at 5% compounded annually compared to 8% quarterly?

1) 30000 = 15000 (1+r/4)^(7*4)

2 = (1+r/4)^28

2^(1/28) = 1 + r/4

2^(1/28)-1 = r/4

r = 4(2^(1/28) - 1) =10.026%

2)

let the 25000 be invested for n years at 5%
100000 = 25000 (1+0.05)^n

4 = (1.05)^n

have to take logs to solve this one

log(4) = n log(1.05)

n = log(4)/log(1.05) = 28.4 yrs so you would need 29 years to get to 100k

now let it be invested for k quarter years at 8% compounded quarterly

100000 = 25000 (1 + 0.08/4)^k

4 = 1.02^k

k = log(4)/log(1.02) = 70 quarter years = 17.5 yrs

the difference is 29 - 17.5 = 11.5 yrs

RomJan 30, 2014

+6248

+1

Quote:
log(4x) = -1

assuming that's a base 10 log

log(4x) = -1

10^(log(4x)) = 10^-1

4x = 10^-1 = 1/10

x = 1/40

RomJan 30, 2014

+6248

+1

Quote:
what are the y intercepts of the graph y=18x^2+9x-5

you need to solve for 0 = 18x^2 + 9x - 5

you can use the quadratic formula

x = (-b +/- sqrt(b^2 - 4ac))/2a

which gives you the solutions to 0=ax^2 + bx + c

in this case
a=18
b=9
c=-5

you can plug the numbers in

RomJan 30, 2014

+6248

+1

Hz is units of 1/s

c is in m/s

so Hz/c = (1/s)/(m/s) = m which is what you expect for wavelength.

you can punch the calculator buttons to get a numeric answer.

RomJan 30, 2014

+6248

+1

Quote:
each 13 feet high and 2 feet in circumference. How much ribbon do I need to wrap each column 8 times?

normal size... all right whatever, let it be an inch.

basically the idea is that you have (13*12)/1 loops of ribbon each 1 circumference long to wrap the column once.

so for 8 times you get

8 * (13*12)/1 * 2 = 416 feet

if the ribbon was 2 inches wide you'd need 208 feet.

RomJan 30, 2014