OEF Vector space definition
    
      --- Introduction ---
    
  
 
This module currently contains 13 exercises on the definition of vector spaces.
Different structures are proposed in each case; up to you to determine whether it is
really a vector space.
See also the collections of exercises on
vector spaces in general or
definition of subspaces.
Circles
Let 
 be the set of all circles  in the (cartesian) plane,	with rules of addition and multiplication by scalars defined as	follows.		- If 
 (resp. 
) is a circle of center	 
 (resp. 
 )	and radius 
,	
 will be the circle of center	
 and radius 
.	
 -  If 
 is a circle of center 
 and radius 
, and if 
 is	a real number, then 
 is a circle of center 
 and radius	
.	
 
	Is 
 with the addition and multiplication by a scalar defined above	 a vector space over the field of real numbers?
Space of maps
Let 
 be the set of maps		 
,	
	(i.e., from the set of  to the set of )	with rules of addition and multiplication by a scalar as follows:	- 	If 
 and 
 are two maps in 
,	 
 is a map	 
	 such that 
 for all 
 belonging to 
.	
 - 	If 
 is a map in 
 and if 
 is a real number,	 
 is a map from 
 to	 
 such that 
	 for all 
  belonging to 
.	
 
	Is 
 with the structure defined above a vector space over	
?
Absolute value
Let 
 be the set of couples 
 of real numbers.	We define the addition and multiplication by a scalar on 
	as follows:	- For any 
 and 
 belonging to 
,	 we define	 
.	
 - For any 
 belonging to 
 and any real number 
,	 we define	 
.	
 
	Is 
 with the structure defined above a vector space over	
?
Affine line
Let 
 be a line in the cartesian plane, defined by an	equation 
, and let	
 be a fixed point on 
. 	We take 
 to be the set of points on 
. On 
, we	define addition and multiplication by a scalar as follows.	
	- If 
 and 
	 are two elements of 
, we define	 
.	
 - If 
 is an element of 
 and if 
 is a real number,	 we define 
.	 
 
	Is 
 with the structure defined above a vector space over	
?
Alternated addition
Let 
 be the set of couples 
 of real numbers.	We define the addition and multiplication by a scalar on 
	as follows:	- For any 
 and 
 belonging to 
,	
.	
 - For any 
 belonging to 
 and any real number 
,	 
.	
 
	Is 
 with the structure defined above a vector space over	
?
Fields
Is the set of all , together with the usual addition and	multiplication, a vector space over the field of ?
Matrices
Let 
 be the set of real 
 matrices. On 
, we	define the multiplication by a scalar as follows.		If 
 is a matrix in 
, and if 
 is a real number, the	product of 
 by the scalar 
 is defined to be the matrix 
,	where 
.	
	Is 
 together with the usual addition and the above multiplication	by a scalar  a vector space over
?	
Matrices II
Is the set of matrices of  elements and of ,	together with the usual addition and scalar multiplication, a vector	space over the field of ?
Multiply/divide
Let 
 be the set of couples 
 of real numbers.	We define the addition and multiplication by a scalar on 
	as follows:	- For any 
 and 
 belonging to 
,	 we define	 
.	
 - For any 
 belonging to 
 and any real number 
,	 we define	 
 if 
 is non-zero, and	
.	
 	
	Is 
 with the structure defined above a vector space over	
?
Non-zero numbers
Let 
 be the set of  real numbers. We define addition	and multiplication by a scalar on 
 as follows:		- If 
 and 
 are two elements of 
, the sum of	 
 and 
 in 
 is defined to be 
.	
 - 	If 
 is an element of 
 and if 
 is a real number,	 the product of 
 by the scalar	 
 is defined to be 
.	
 
	Is 
 with the structure defined above a vector space over	
?
Transaffine
Let 
 be the set of couples 
 of real numbers.	We define the addition and multiplication by a scalar on 
	as follows:		- If 
 and 
 are two elements of 
,	 their sum in 
 is defined to be the couple	 
.	
 - If 
 is an element of 
, and if 
 is a real number,	 the product of 
 by the scalar 
 in 
 is defined	 to be the couple	 
.	
 
	Is 
 with the structure defined above a vector space over	
?
Transquare
Let 
 be the set of couples 
 of real numbers.	We define the addition and multiplication by a scalar on 
	as follows:	- For any 
 and 
 belonging to 
,	 
	
 - 	For any 
 belonging to 
 and any real number 
,	  
.	
 
	Is 
 with the structure defined above a vector space over	
?
Unit circle
Let 
 be the set of points on the circle	
 in the cartesian plane.	For any point 
 in 
, there is a real number 
 such that	
, 
.		We define the addition and multiplication by a scalar on	
 as follows:	
	- 	  If 
 and 
	 are two points in 
, their sum is defined to be	 
.	
 - 	If 
 is a point in 
	 and if 
 is a real number, the product of	 
 by the scalar 
 is defined to be	 
.	
 
	Is 
 with the structure defined above a vector space over	
?
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    - Description: collection of exercices on the definition of vector spaces. interactive exercises, online calculators and plotters, mathematical recreation and games
 
    - Keywords: interactive mathematics, interactive math, server side interactivity, algebra, linear_algebra, vector_space