All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars
 perplexus dot info

 Simultaneous Settlement (Posted on 2012-01-27)
Without solving for x and y, determine all possible values of x*y in this simultaneous equation:

x+x*y = 8 and, y+x*y = 9

Note: Solving for 1/x, 1/y, -x or -y is similarly NOT allowed.

 No Solution Yet Submitted by K Sengupta Rating: 5.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
 One way Comment 8 of 8 |

Not sure what the previous answers were, but here is one way:

x=8-xy ; y=9-xy
multiply these together
xy=(8-xy)(9-xy)
xy=72 - 17xy + (xy)^2
(xy)^2 -18xy + 72 = 0
xy = (18 +/- sqrt(324-288))/2
xy = 9 +/- 3
xy = {6, 12}

 Posted by Larry on 2012-01-28 15:45:54
Please log in:
 Login: Password: Remember me: Sign up! | Forgot password

 Search: Search body:
Forums (1)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (10)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2020 by Animus Pactum Consulting. All rights reserved. Privacy Information