Re: Factoring problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg35503] Re: [mg35499] Factoring problem*From*: BobHanlon at aol.com*Date*: Wed, 17 Jul 2002 02:08:48 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

In a message dated 7/16/02 6:21:34 AM, shodgen at mindspring.com writes: >I've decided to see if any of you can factor this eq. since it's not >possible to have Mathematica show intermediate steps when factoring. This >is a problem from my precalc book, and the instructor of the class hasn't >been able to get to the final answer either. I've tried and tried using >grouping in various ways, as well as other techniques. > >I'd appreciate it if anyone can figure this out, since I just can't get >over >this problem. > >Original problem: > y^4 - (p + q)*y^3 + (p^2*q + p*q^2)*y - p^2*q^2 >Answer in book: > (y^2 - p*q)*(y - p)*(y - q) > Since you know the answer, work the problem backwards. (y^2 - p*q)*Expand[(y - p)*(y - q)] ((-p)*q + y^2)*(p*q - p*y - q*y + y^2) % // Expand (-p^2)*q^2 + p^2*q*y + p*q^2*y - p*y^3 - q*y^3 + y^4 %//Collect[#,y]& (-p^2)*q^2 + (p^2*q + p*q^2)*y + (-p - q)*y^3 + y^4 Bob Hanlon Chantilly, VA USA