Rom

7 Questions
2456 Answers

+9

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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

1761

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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1805

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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

1302

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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

1699

1

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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

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0

Quote:
how can i calculate ln(9*10^-5)?

ln(ab) = ln(a) + ln(b)
ln(a ^b) = b ln(a)

ln(9*10 ^-5) = ln(9) + (-5ln(10)) = ln(9) - 5ln(10)

RomFeb 7, 2014

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0

Quote:
how do i put 450,900,800 in scientific notation?

scientific notation is of the form

a x 10 ^b where usually 0 < a < 10, this is called normalized scientific notation

start to the right of the last digit to the left of the decimal point (or the last digit if there is no decimal point)
count to the left until you are to the right of the first digit. That will be your value of b. In this case it's 8.

Then write the number as the first digit [size=150].[/size] the rest of the digits until the last non-zero one. In this case that would be

4.509008

Now multiply this number by 10 ^b which in this case is 10 ⁸ and the final answer is

4.509008 x 10 ⁸

RomFeb 7, 2014

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0

Quote:
Hey guys, expanding factored equations and simplifying them has my head in a knot.

Any extremely helpful advice to get past it? (no need to resolve except for the last couple if you're generous.)

The questions format is varied, ie.
(2-x)(1-x) (struggling)

(3x-9y) -> got this type easily.

(1/2x + 1/4y) -> i got 1/4(1/4x+y) but think it's wrong.

it is. You can't afford to not be able to do simple arithmetic like this if you're going into EE.

(1/2x + 1/4y) = 1/4(2x + y)

Quote:

(3x+1)(2x+1) -> which posed the question, how do I know if a number attributed to x or just a solo number was factored? (struggling)

this is already factored. I'm not sure what you are asking here.

Quote:

1/3x + 1/6xy -> have not really attempted this in the last few days. But I can do it.

2/3pi3+1/3pi2h. -> do solve please. I get that pi can be same as x in the equation but that isn't my issue trying to solve it.

I don't know what this is. do you mean

(2/3) pi ³ + (1/3) pi ²h ?

if so it's (1/3)pi ²(2pi + h)

Quote:

also

2x2(x-5)-x(x-2)-3x(x-5)

this is just arithmetic. just multiply everything out.

Quote:

5x2-4x-1 (can solve with lots of thoughts.

Quote:

16x2-1

difference of 2 squares
(4x-1)(4x+1)

my advice to you is to practice these types of problems until you can do them as easily as you can add 2 and 2.
If you can't whip through this sort of stuff pre-calculus is going to be h**l.

RomFeb 7, 2014

+6251

0

Quote:
Using imaginary numbers, what is the √-16?

i = sqrt(-1)

sqrt(ab)=sqrt(a)*sqrt(b)

-16 =(16) (-1)

sqrt(-16) =sqrt(16)*sqrt(-1)

sqrt(-16) = 4*i = 4i

RomFeb 7, 2014

+6251

0

Quote:
What is ln(8.66×10⁻⁷ / 3.61×10⁻¹⁵)

log(ab) = log(a) + log(b)

log(a/b) = log(a) - log(b)

ln(a) = log(a)/log(e) where ln(e) = 1

so first find

log(8.66×10⁻⁷ / 3.61×10⁻¹⁵) = (log(8.66) + (-7)) - (log(3.61) + (-15)) =

0.38 + (15-7) = 8.38

Now we convert to natural log ln by finding

8.38 / log(e) = 19.30

RomFeb 7, 2014

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0

Quote:
a bag of skittles contained 13 reed, 15 yellow, 44 brown, 12 orange, and 9 green candies. What percent of the candy was red?

divide the number of red skittles by the total number of skittles and then multiply by 100 to get percent.

RomFeb 7, 2014

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0

Quote:
GAYYY

That's ok, we don't care, we'll answer your math questions anyway.

RomFeb 6, 2014

+6251

0

please rewrite all of this properly using parentheses. I can't figure out the expressions you actually mean.

RomFeb 6, 2014

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Quote:
How do you go about solving this problem sqrt(sqrt(1+x) + 1-x)) and would you find the domain

do you mean solving for x given that sqrt(sqrt(1+x) + (1-x)) = C, where C is some number?

if so

sqrt(sqrt(1+x) + (1-x)) = C

sqrt(1+x) + (1-x) = c ²

sqrt(1+x) = (x-1) + c ²

1+x = ((x-1) + c ²) ² = (x-1) ² + 2c ²(x-1) + c ⁴

now you can collect all the terms together and end up with a quadratic expression in x which you can solve using the quadratic formula.

As far as the domain is concerned none of the terms under radicals can be negative. So

(1+x) >= 0 ---> x >= -1

(sqrt(1+x) + (1-x)) >= 0

sqrt(1+x) >= (x-1)

1+x >= (x-1) ²

and this is also a quadratic expression that can be solved using basic methods.

RomFeb 6, 2014