Membres: Rom

7 Questions
2456 Answers

1251

+6252

is there any point to answering these anymore?

Does anyone even look at the answers given?

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Rom 3 mars 2020

1830

+6252

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]
lire plus ..

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Rom 8 août 2019

1829

+6252

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.
lire plus ..

Hors sujet

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Rom 4 janv. 2019

1321

+6252

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.
lire plus ..

Rom 27 nov. 2018

1503

+6252

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

Hors sujet

GingerAle ●●●●●●●●

Rom 15 nov. 2018

+26

3071

+6252

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 16 oct. 2015

1727

+6252

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?

Melody ●

Rom 30 janv. 2014

+6252

Quote:
A4273B is 6 digit no. in which A and B are digits and the no. is divisible by 72. Find A and B

this number is

N = 100000A + B + 42730 and

N mod 72 = 0

42730 mod 72 = 34

100000 mod 72 = 64 so

N = 64A + B + 34 = 0 (mod 72)

(64A+34) mod 72 = 72 - B

at this point I don't know anything more clever than making a small table and looking for A such that

(64A+34) mod 72 is within 9 of 72

doing this you find A=5 and B=6

542736 / 72 = 7538

Rom17 févr. 2014

+6252

Quote:
what is 1/4 times 4 to the power of 3/2

there are a few ways to go about this, probably the easiest is

(1/4) 4 ^(3/2) =

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

(1/4)(4 * 4 ^(1/2)) =

1 * 4 ^(1/2) =

4 ^(1/2) =

sqrt(4) = 2

Rom17 févr. 2014

+6252

Quote:
How to find an angle between a found magnitude vector and the x-axis

a general vector can have both any magnitude >= 0
and any angle.

So if you are just given the magnitude of a vector there's no way to calculate it's angle from the x-axis. You need more info.

Rom17 févr. 2014

+6252

as your concrete example

log ₄(78) = log ₁₀(78) / log ₁₀(4)

Now you talk about calculating these things manually. I'm not entirely sure what you mean by that. Even for base 10 logs eventually you're going to be reduced to one of 3 ways of getting the actual value

a) punching the buttons on your calculator
b) looking the value up in a table
c) approximating it by it's series or perhaps some other approximation formula

unless of course the argument is a power of the base in which case the log is just that power, for example

log ₁₀(1000) = log ₁₀(10 ³) = 3
log ₄(1024) = log ₄(4 ⁵) = 5

without using one of the methods a-c above about the best you can do is note that

4 ³ = 64 < 78 < 256 = 4 ⁴

and thus 3 < log ₄(78) < 4

back in the old days before electronic calculators (and yes I was alive back then) all we had was tables of base 10 logs and every problem involving logs first had to be converted to base 10 using the formula I gave you, and then done in base 10 and converted back if necessary. With pencil and paper (or a slide rule if you had one).

If you're interested in the series I'm referring to in (c) above you can read about it here. http://en.wikipedia.org/wiki/Logarithm#Calculation

Rom17 févr. 2014

+6252

Quote:
4 gallons equals how many cups?

8 oz to a cup
2 pints to a quart
4 quarts to a gallon

4 gallon = 4 gallon * 4 quart/gallon * 2 pint/quart * 8 oz/pint = 256 oz

notice how all the units cancel each other out until you're left with oz at the end.

Rom17 févr. 2014

+6252

log _b(x) = log _c(x) / log _c(b)

so

log ₁₀(x) = log _c(x) / log _c(10)

Rom17 févr. 2014

+6252

Quote:
Here is a sequence of 3 numbers:
13
202
2626

What is the next number in the sequence?

13
202 = 101x2
2626 = 101x2x13

So the next number should be

101x2x13x202 = 530452

Rom15 févr. 2014

+6252

don't sweat it

Rom14 févr. 2014

+6252

Quote:
how many atoms are contained in 2.45 grams of sulfur

The Molar mass of S = 32.065 g/mole

The number of atoms, N, of an element is Avogadro's number times the number of moles of the element

N = 6.0221413x10 ²³ x 2.45/(32.065) = 4.6x10 ²²

Rom14 févr. 2014

+6252

ft ² = ft * ft = (yd/3) (yd/3) = yd*yd/9 = yd ²/9

Rom14 févr. 2014

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