MHB Solve Fractions Problem: Slope at (1,3)

[tmt1]

I have this derivative and I need the slope at (1,3).

y' = [3(y-x)^2 -2x]/[3(y-x)^2]

With this equation I plug in x and y and the slope equals 5/6.

However, can't y' be simplified further to:

y' = [3(y-x)^2]/[3(y-x)^2] -2x/[3(y-x)^2] ?

Thus can't it be simplified to:

y'= -2x/[3(y-x)]^2

thus the slope would be -1/6 when I plug in x and y.What am I doing wrong?

Thanks for all your help!

 

[MarkFL]

Hint: $$\frac{a}{a}=1$$ where $$a\ne0$$

You are trying to say $$\frac{a}{a}=0$$.

 

[Pindrought]

Hopefully this helps.

EDIT: Fixed Image

Get it now?