# Math Help - [SOLVED] X=1 Solve

1. ## [SOLVED] X=1 Solve

My teach said there was a common factor to factor out before i can substitute the value of 1 in for x, but i have no clue how to find it..

(3-x)/(3x^2-9x)

if i put zero in on the bottom it becomes 0 and i can't divide by zero, someone please show me their solutions, don't skip any steps please (and if u could, explain some of the steps that would be great)

2. (3-x)
________
(3x^2-9x)

Now, we see that both 3x^2 and 9x are divisible by 3 (3x3, 3x1) and they also share x (x^2 = x*x). So we can change that into:

(3-x)
________
3x(x-3)

Here, we notice that (3-x) = -(x-3), so

-(x-3)
______
3x(x-3)

Divide both sides of the fraction by (x-3):

-1
___
3x

Now, input x=1 here to get -1/3

Note that if you want to graph this, the original domain still applies.

3. Originally Posted by Noxide
My teach said there was a common factor to factor out before i can substitute the value of 1 in for x, but i have no clue how to find it..

(3-x)/(3x^2-9x)

if i put zero in on the bottom it becomes 0 and i can't divide by zero, someone please show me their solutions, don't skip any steps please (and if u could, explain some of the steps that would be great)
do you mean substitute 3 for x ?

$\frac{3-x}{3x^2 - 9x} = \frac{3-x}{3x(x - 3)} = -\frac{x-3}{3x(x-3)}$

4. How does one get that fancy math writing?
It sure beats how I did it... Is there a page explaining the syntax?

5. Originally Posted by Lord Voldemort
How does one get that fancy math writing?
It sure beats how I did it... Is there a page explaining the syntax?
Click on the fifth link in my signature.