All Answers

Vraces:
A radioactive kalashnikov gets less radioactive every year. After 60 years only 25% of the radio-activeness remains.
What is the yearly reducing of radio-activeness in percent?

Hi Vraces,
You have to let r be a decimal . That is, if it was 2% then r=0.02 (that's just an example)

S is future value, P is present(or original) value, r is yearly rate reduction and n is the number of years.

S=P(1-r) ⁿ

Now, when n=60, S=P/4, find r

You see if you can finish it.

MelodyJan 22, 2014

+118725

kitty<3:
x/5-4(x-5)/3=2x/3+5

Well, this is sort of confusing.
I'm assuming that you've put parentheses in all the places you need them(?)

Then, you can start by multiplying both sides by the same number so that x is not a fraction.

Thanks Kitty,
This one is a lttle confusing. You are best to put brackets in even if you know you don't need them for a question like this because then we know for sure that we are answering the question that you intended.

(x/5) - [4(x-5)/3] = [2x/3] +5

now the denominators(bottoms) are 5, 3, and that's it. The lowest common denominator is 15.
Write you fractions properly, not like in the forum, put a big bracket around both sides(separately) and multiply both sides by 15. that will get rid of all your fractions.
I think that Kitty and I will let you do it from there.
Happy calculations.
if you really get stuck, or you want someone to check your working, you can post again.

MelodyJan 22, 2014

+118725

mikaela:
how do I set a binary?

What do you mean?

MelodyJan 22, 2014

+118725

mcelhattan:
what is 190-120=

Now, how many times do you have to put the same junky question in?

MelodyJan 22, 2014

+118725

lala:
:D what is the absolute value equations of |3a -8| + 4 = 11

|3a -8| = 7

you have to solve
3a-8 = 7 or 3a-8 = -7
there will be 2 answers

MelodyJan 22, 2014

+118725

mcelhattan:
what is 190-120=

why can't you do this yourself?

MelodyJan 22, 2014

+118725

Guest:
solve(sqrt((0-3)x-2)

sqrt(-3x-2)

you can't do anymore than this BUT you should realize that you can't find the sqrt of a negative number therefore

-3x-2 >= 0
-3x>=2
x<=-2/3

x has to be less than or equal to -2/3, otherwise there is no solution (in the real number system)

MelodyJan 22, 2014

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anil:
how to do antilog?

I know that you have the question in the title, which is good BUT
you need to put the question in the question as well

(antilog of 2) + (0.009) I am assuming that this is base 10

=10 ² + 0.009

MelodyJan 22, 2014

+118725

des:
y=1/2x+4 solve for y in terms of x

y = 1/2 * x + 4

now the idea is to get the x on one side by itself. So you need to keep thinking, what can I get rid of and how do I do that.

What is the opposite of adding 4 ? Well taking it away of course. But you have to do it to both sides.

y-4 = 1/2 * x +4-4

y-4 = 1/2 * x

Now what is the opposite of halving something. How about timesing it by 2.

2(y-4) = 2 * 1/2 * x Don't forget the brackets

x=2(y-4)

MelodyJan 22, 2014

+118725

Princess Sophie E:
A small block of weight W is placed on a plane inclined at an angle x to the horizontal.
A) when x=20 degrees, the block is in limiting equilibrium. Find the coefficient of friction.
B) when the coefficient of friction=1/3 and x=30 degrees, a horizontal force of 6N is required to prevent the block from slipping down the plane. What is the value of W?

Hi Princess Sophie,
I have been looking at your question but I am not a physics teacher. i was hoping that a bright physics student would come along and help you but so far that hasn't happened.
I would suggest that you post your question in physicshelpforum.com or mathhelpforum.com both are better suited to your level of study.
In both these forums you will be expected to be interactive in your learning. Even when you post your question you will need to state what you already know or what you have done towards answering your own question.
I hope that this is some degree of help.
sorry.

I did find a couple of web pages that may be of use to you
http://www.mathsrevision.net/advanced-level-maths-revision/mechanics/coefficient-friction
and
http://www.youtube.com/watch?v=c2bO20DFcpA

MelodyJan 22, 2014