
Geometry Geometry Math Forum 
 LinkBack  Thread Tools  Display Modes 
May 31st, 2017, 04:19 PM  #1 
Newbie Joined: May 2017 From: united kingdom Posts: 1 Thanks: 0  Vectors: where k is a scalar quantity Hello, I'd really appreciate some help with this particular question on vectors. The website is not offering answers. The question is: In the diagram above (not drawn to scale) X is the point on AB such that AX:XB=9:4. The position vector of A is 3a and the position vector of B is 3b. Find the value of k if OX=k(4a+9b) where k is a scalar quantity. Thanks so much! 
May 31st, 2017, 04:56 PM  #2 
Global Moderator Joined: Dec 2006 Posts: 18,137 Thanks: 1415 
k = 3/13

May 31st, 2017, 05:26 PM  #3 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,030 Thanks: 2341 Math Focus: Mainly analysis and algebra 
Find $\vec{AB}$. Then use $\vec{AX}=\frac9{13}\vec{AB}$ (why?). And finally $\vec{OX}=\vec{OA}+\vec{AX}$.

May 31st, 2017, 11:24 PM  #4 
Newbie Joined: Apr 2017 From: Bhadohi, U.P., India Posts: 23 Thanks: 1 
use of section formula: OX = [9(3a) + 4(3b)]/(9+4) = (9a+4b)3/13 

Tags 
quantity, scalar, vectors 
Search tags for this page 
Click on a term to search for related topics.

Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
quantity (in hundreds)  blimper  Algebra  1  August 27th, 2016 12:58 PM 
Quantity analysis  winter16  Applied Math  1  January 28th, 2016 12:38 PM 
Scalar Products, Derivatives and Unit Vectors  Ben Hunto  Physics  2  March 5th, 2015 04:10 AM 
Scalar vectors : need help in proving  rnck  Applied Math  4  September 14th, 2012 08:25 AM 
Differentiating Vectors and Gradient of a Scalar Field?  cypher  Linear Algebra  3  June 29th, 2010 02:40 PM 