# Math Help - Simple Formula?

1. ## Simple Formula?

Hey guys.

I'll be honest, I haven't studied algebra in years. Last night though, I was shocked to find that I did actually want to solve an equation. I can't really rmemeber how it came about but I do remember working on it for quite a while and not getting anywhere... But it seems quite basic. Maybe you lot can help?

What do you reckon? Is there something I can replace the question mark with?

2. Originally Posted by matteus12
Hey guys.

I'll be honest, I haven't studied algebra in years. Last night though, I was shocked to find that I did actually want to solve an equation. I can't really rmemeber how it came about but I do remember working on it for quite a while and not getting anywhere... But it seems quite basic. Maybe you lot can help?

What do you reckon? Is there something I can replace the question mark with?
You have: (n/?)^2 = 2n

find the square root of both sides: n/? = SQRT(2n)

Multiply both sides by ? to get: n=?SQRT(2n)

Divide both sides by the sqrt(2n) to get: n/SQRT(2n)=?

Now we need to rationalize the denominator: (nSQRT(2n))/(2n)=?

Which simplifies to: SQRT(2n)/2=?

3. Originally Posted by matteus12
Hey guys.

I'll be honest, I haven't studied algebra in years. Last night though, I was shocked to find that I did actually want to solve an equation. I can't really rmemeber how it came about but I do remember working on it for quite a while and not getting anywhere... But it seems quite basic. Maybe you lot can help?

What do you reckon? Is there something I can replace the question mark with?
Let's call ? x. then what you have is:

(n/x)^2=2n

or:

(n/x)(n/x)=2n

Cancel one of the n's, and collect the x's:

n/x^2=2,

multiply both sides by x^2:

n=2 x^2

or:

x^2=n/2

so x= +/- sqrt(n/2)

RonL

4. I follow you right up to "so x= +/- sqrt(n/2)"?

It's probably just the way it's written. How would I write that normally?

Edit: Haha, never mind. I got it! It was just the way I was reading it.

Thanks everyone.