It seems you've both solved for x or y.
Jer, you have x = 8 - a, broll, you have y=x+1.
It's my understanding this is against the rules. It seems easy enough to work around the rules, though. Here's Jer's solution with a small modification.
"Let xy = a so also y = a/x
Substitute into the first equation gives x + a = 8 then rewrite this as x +1 = 8 - a +1
Substitute into the second equation gives a/x + a = 9 then solve for x +1 gives x +1 = a/(9-a) +1
Substitute now for each x +1: (the rest of the solution follows exactly)
8 - a +1= a/(9-a) +1
8 - a = a/(9-a)
72 - 17a + a^2 = a
a^2 - 18a + 72 = 0
this quadratic has solutions
a= 6 or a=12
so the possible values of x*y are 6 and 12"
I don't know if this is allowed. We're not allowed to solve for x, are we allowed to solve for x+1?
Edited on January 27, 2012, 5:57 pm
Edited on January 27, 2012, 5:59 pm
Posted by Dustin
on 2012-01-27 17:54:57