1
   

If A2 + B2 = 15 and AB = 10

Forums: Math, Homework, Algebra
Email this Topic • Print this Page
 
 
AndyCharles
 
Reply Fri 14 Oct, 2011 05:01 am
If A2 + B2 = 15 and AB = 10, what is the value of the expression
(A – B)2 + (A + B)2 ?

(a) 10.
(b) 20.
(c) 30.
(d) 60.
(e) 70.

Thanks a lot.
Andy Charles
  • Topic Stats
  • Top Replies
  • Link to this Topic
Type: Question • Score: 1 • Views: 1,321 • Replies: 2
No top replies

 
engineer
 
  2  
Reply Fri 14 Oct, 2011 05:08 am
@AndyCharles,
(a-b)^2 = a^2 - 2ab + b^2
(a+b)^2 = a^2 + 2ab + b^2
-----------------------------------------
= 2 a^2 + 2 b^2

Since a^2 + b^2 = 15, twice that is 30.
0 Replies
 
raprap
 
  1  
Reply Fri 14 Oct, 2011 08:52 am
@AndyCharles,
complete the squares and add

hint the ab term cancels

Rap
0 Replies
 
 

Related Topics

Amount of Time - Question by Randy Dandy
What is the general formula for this math problem? - Question by Emarin
logical number sequence riddle - Question by feather
Interest rate risk and backtesting - Question by kjmed
Are there any science careers for people who hate math - Question by aja2015
Calc help needed - Question by mjborowsky
HELP! The Product and Quotient Rules - Question by charsha
STRAIGHT LINES - Question by iqrasarguru
Possible Proof of the ABC Conjecture - Discussion by oralloy
Help with a simple math problem? - Question by Anonymous1234567890
How do I do this on a ti 84 calculator? - Question by Anonymous1234567890
 
  1. Forums
  2. » If A2 + B2 = 15 and AB = 10
Copyright © 2024 MadLab, LLC :: Terms of Service :: Privacy Policy :: Page generated in 0.1 seconds on 12/22/2024 at 12:28:21
▲ ▼