[lit-ideas] Re: Don't Laugh (Math)

  • From: "Peter D. Junger" <junger@xxxxxxxxxxxxxxxxxxxx>
  • To: lit-ideas@xxxxxxxxxxxxx
  • Date: Fri, 23 Jun 2006 18:17:47 -0400

Erin Holder writes:

: OK, who can explain to me how to solve this:
: If     x^2+2xy+y^2 = 9      then   (x+y)^4 = ? 
: I know the answer is "81", I just don't know how to get it.  It's starting to
: frustrate me.  I haven't done this stuff in almost ten years, and I can't for
: the life of me remember how to go about it (although I seem to be getting the
: hang of some of the other ones...?)
A better way to solve and remember how to solve the problem may be to 
realize that if you factor x^2+2x+y^2 you get (x+y)(x+y) which
equals (x+y)^2 which you are told equals 9.  Now the square of
(x+y)^2 is (x+y)^4 which equals 9^2 which equals 81.

It's hard to do this stuff in ASCII.

Good luck,
Peter D. Junger--Case Western Reserve University Law School--Cleveland, OH
 EMAIL: junger@xxxxxxxxxxxxxxxxxxxx    URL:  http://samsara.law.cwru.edu   
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