Question
Assertion : There are only finitely many 2 × 2 matrices which commute with the matrix
Reason : If A is non-singular then it commutes with I, adj A and A–1
- If both (A) and (R) are true, and (R) is the correct explanation of (A).
- If both (A) and (R) are true but (R) is not the correct explanation of (A).
- If (A) is true but (R) is false.
- If (A) is false but (R) is true.
The correct answer is: If (A) is false but (R) is true.
The reason R is true since
AI = IA, AA–1 = A–1A = I, A|adj A| = |adj. A|A
But a matrix can commute with general order matrices which may be infinite in number.
Let B = be a matrix which commute with A then AB = BA
=
= =
a + 2c = a – b, b + 2d = 2a – b, – a – c= c – d, – b – d = 2c – d
The above four relations are equivalent to only two independent relations
a – d = b, b + 2c = 0
If d = , then a = b + = –2c +
Thus, are all possible 2 × 2 matrices which commute with given matrix A =
and c being any arbitrary complex numbers. Thus assertion is therefore false.
Related Questions to study
Statement-I The equation has exactly one solution in [0, 2].
Statement-II For equations of type to have real solutions in should hold true.
In this question, we have to find the statements are the correct or not and statement 2 is correct explanation or not , is same like assertion and reason. Here, Start solving first Statement and try to prove it . Then solve the Statement-II . Remember cos a cosb -sin a sinb = cos ( a + b ) and sin a cosb + cosa sinb = sin( a+ b) .
Statement-I The equation has exactly one solution in [0, 2].
Statement-II For equations of type to have real solutions in should hold true.
In this question, we have to find the statements are the correct or not and statement 2 is correct explanation or not , is same like assertion and reason. Here, Start solving first Statement and try to prove it . Then solve the Statement-II . Remember cos a cosb -sin a sinb = cos ( a + b ) and sin a cosb + cosa sinb = sin( a+ b) .