math

leslie

New Member
I'm doing the practicse test for college entrance exams :scared:

can someone explain to me how

5x^2/25x+5x^2 is solved?
 

leslie

New Member
if ax=c-x then x=

:mope:

I have the answers, I just don't get how to get there on some of these...and that's scary :(
 

leslie

New Member
if 4x/5=11 + x/4 then x=

it's all these rules I've forgotten...one I hear them again I think I'll be ok...
 

Nixy

Administrator
Staff member
OK, I will start from post one and explain each one :)

Styarting in the next post :D
 

Nixy

Administrator
Staff member
leslie said:
I'm doing the practicse test for college entrance exams :scared:

can someone explain to me how

5x^2/25x+5x^2 is solved?

So, essentially you have:

(5*x*x)/(25*x + 5*x*x)

"dividing out" a factor of 5x you get:

x/(5 + x)

If that is all the question is I think that would be as far as you woudl be expected to go :)
 

Nixy

Administrator
Staff member
leslie said:
if ax=c-x then x=

:mope:

I have the answers, I just don't get how to get there on some of these...and that's scary :(

ax = c - x

First thing to do is to make sure all the variables (x) are on the same side. Keeping in mind that what you do to one side you must do to the other.

So, ax + x = c - x + x

Leaving you with: ax - x = c

Common factor the x gives you : x(a - 1) = c

Therefore: x = c/(a - 1)
 

Nixy

Administrator
Staff member
leslie said:
:(

getting frustrated...

a^2/9 - 4/25 in a factored form is -

(a^2)/9 - 4/25 is a difference of squares since all the terms have perfect roots. The formula for factoring a difference of squares is:

a^2 - b^2 = (a - b)(a + b)

So, (a^2)/9 - 4/25 = (a/9 - 2/5)(a/9 + 2/5)
 

Nixy

Administrator
Staff member
leslie said:
if 4x/5=11 + x/4 then x=

it's all these rules I've forgotten...one I hear them again I think I'll be ok...

4x/5 = 11 + x/4

First step is to get a common denominator. The LCD for 5, 1 and 4 woudl be 20.

So, 16x/20 = 220/20 + 5x/20

This is the same as: 16x = 220 + 5x

From here you rearrange and solve:

16x - 5x = 220 +5x - 5x
11x = 220
x = 20
 

Nixy

Administrator
Staff member
leslie said:
last one I don't get...

if m=1/3rb^2 then b=

m = 1/3rb^2

You can use cross mutilplication here. The general rule is:

If a/b = c/d, then ad = bc

So, m(3rb^2) = 1
Since it's multiplication you can move the brackets whereever you want since they don't reall yhave a purpose except to visually seperate.

So, (m3r)b^2 = 1
Divide each side by (m3r) and you are left with b^2 = 1/(m3r)

Therefore b = Square root of (1/(m3r))
 

Nixy

Administrator
Staff member
If you need anything else I will be back and forth here all day and also might have ICQ on. i am going to PM you my work email though because excluding my hour lunch you should beable to reach me at that right up until 5pm :)
 

leslie

New Member
I think I have a lot of studying to do...

I aced this test 10 years ago and now I feel like I know nothing again :retard:

but seeing it all broken down again helped...now I am remembering :)
 

Neo

Administrator
Staff member
now i remember why i didnt want anything to do in the accounting or scientific field. I hated all that rubbish back then and still do. It was one of those things i learned to get the work done and then erased it from my memory banks when finished.
Now the boys are in school and ill prolly have to relearn some of it to help them with homework.
 
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