Ask Questions, Get Answers
Menu
X
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
15 Test Series
CBSE XII
Math
JEEMAIN
Math
Physics
Chemistry
Practice Test Series
CBSE XI
Math
NEET
Physics
Chemistry
Biology - XII
Biology - XI
Olympiad class V
Math - 5 Test Series
Olympiad class VI
Math - 5 Test Series
studyplans
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
15 Test Series
CBSE XII
Math
JEEMAIN
Math
Physics
Chemistry
Practice Test Series
CBSE XI
Math
NEET
Physics
Chemistry
Biology - XII
Biology - XI
Olympiad class V
Math - 5 Test Series
Olympiad class VI
Math - 5 Test Series
mobile
exams
ask
sample papers
tutors
pricing
login
X
ASK
Home
>>
CBSE XII
>>
Math
>>
Model Papers
Let * ba a binary operation on set Q of rational defined as \( a*b=\large\frac{ab}{5}.\) Write the identity for * , if any.
cbse
class12
modelpaper
2012
sec-a
q1
easy
math
Share
asked
Feb 9, 2013
by
thanvigandhi_1
edited
Oct 1, 2013
by
sreemathi.v
Please
log in
or
register
to add a comment.
Please
log in
or
register
to answer this question.
1 Answer
Toolbox:
An element $e \in N $ is an identify element for operation * if $a*e=e*a$ for all $a \in N$
Let $e$ be the identity element in $Q^+$.
Then $a\ast e=e\ast a$ for all $a\in Q^+$
$\Rightarrow \large\frac{ae}{5}$$=a$
and $\large\frac{ae}{5}$$=a$ forall $a\in Q^+$
$\Rightarrow e=5$
Hence $5$ is the identity element in $Q^+$
answered
Oct 1, 2013
by
sreemathi.v
Please
log in
or
register
to add a comment.
Related questions
Let * be a binary operation on set Q of rational numbers defined as a*b = \( \large\frac{3ab}{7} \). Write the identity for * , if any.
cbse
class12
modelpaper
2012
sec-a
q1
math
asked
Dec 24, 2012
by
thanvigandhi_1
0
answers
Let * be binary operation on Q defined by $ a*b=\large\frac{3ab}{5} $ show that * is commutative as well as associative. Also find its identity element if it exists.
cbse
class12
modelpaper
2012
sec-b
q12
math
asked
Feb 4, 2013
by
thanvigandhi_1
0
answers
Let * be binary operation of N x N defined by (a,b)*(c,d)=(a+c,b+d). Show that * is commutative as well as associative. Find the identity element for the operation * on N x N, if any.
cbse
class12
modelpaper
2012
sec-b
q11
math
asked
Feb 2, 2013
by
thanvigandhi_1
0
answers
Let * be binary operation of N x N defined by (a,b)*(c,d)=(a+c, b+d). Show that * is commutative as well as associative. Find the identity element for the operation * on N x N, if any.
cbse
class12
modelpaper
2012
sec-b
q11
math
asked
Jan 31, 2013
by
thanvigandhi_1
0
answers
On Q the set of all rational numbers, a binary operation $\ast$ is defined by $a \ast b=\frac{ab}{5}$ for all $a, b \in Q $. Find the identity element $\ast$ in Q. Also prove that every non-zero element of Q is invertible.
cbse
class12
maths
sec-e
ch1
asked
Nov 20, 2016
by
priyanka.c
1
answer
A binary operation * on the set (0,1,2,3,4,5} is defined as : $ f(x) = \left\{ \begin{array}{l l}a+b, & \quad if { a+b < 6} \\ a+b-6, & \quad if { a+b \geq 6} \end{array} \right. $ Show that zero is the identity for this operation and each element 'a' of the set is invertible with 6-a, being the inverse of 'a'.
cbse
class12
modelpaper
2012
sec-b
q11
medium
math
asked
Feb 5, 2013
by
thanvigandhi_1
1
answer
Let A = N x N and * be a binary operation on A defined by (a,b)*(c,d)=(ac,bd), show that : (i) (A*) is commutative. (ii) (A*) is associative (iii) Find the identity element, if any, in A.
cbse
class12
modelpaper
2012
sec-c
q23
math
asked
Jan 31, 2013
by
thanvigandhi_1
0
answers
Ask Question
Tag:
Math
Phy
Chem
Bio
Other
SUBMIT QUESTION
►
Please Wait
Take Test
JEEMAIN Crash Practice
15 Test Series
NEET Crash Practice
15 Test Series
JEEMAIN
350+ TESTS
NEET
320+ TESTS
CBSE XI MATH
50+ TESTS
CBSE XII MATH
80+ TESTS
...