Identity element - Jamb Mathematics Past Questions and Answers

Question 6:

• JAMB 2001

⊗	k	l	m
k	l	m	k
l	m	k	l
m	k	l	m

The identity element with respect to the multiplication shown in the table above is

A. O
B. M
C. L
D. K

Question 7:

• JAMB 2005

An operation * is defined on the set of real numbers by a * b = ab + 2(a + b + 1). find the identity element

A. 2
B. 1
C. -1
D. -2

Question 8:

• JAMB 2006

A binary operation \(\oplus\) defined on the set of real number is such that x\(\oplus\)y = xy/6 for all x, y ∈ R. Find the inverse of 20 under this operation when the identity element is 6

A. ¹/₁₂
B. ¹⁰/₃
C. ¹/₂₀
D. ⁹/₅

Question 9:

• JAMB 2007

A binary operation Δ is defined by aΔb = a + b + 1 for any numbers a and b. Find the inverse of the real number 7 under the operation Δ, if the identity element is -1

A. -7
B. -9
C. 5
D. 9

Question 10:

• JAMB 2008

A binary operation on the real set of numbers excluding -1 is such that for all m, n ∈ R, mΔn = m+n+mn. Find the identity element of the operation.

A. 1
B. Zero
C. -¹/₂
D. -1