Question 819190
{{{((y-1)(y-3))/((3-y)(1+y))}}}
The "trick" with this one is recognizing that y-3 and 3-y are not the same... but they are opposites of each other! So if we factor out a -1 from one of them (not both!), we will have some factors to cancel:
{{{((y-1)(-1)(3-y))/((3-y)(1+y))}}}
{{{((y-1)(-1)cross((3-y)))/(cross((3-y))(1+y))}}}
leaving...
{{{((y-1)(-1))/(1+y)}}}
All that's left is to multiply out the numerator:
{{{(-y+1)/(1+y)}}}