BT-FT07 matrix

Statement 1: If A and B are two matrices such that AB = A, then B is a square matrix
and
Statement 2: The product AB exists only if A is of order m × n and B is of order n × n.

1.
Statement 1 is True, statement 2 is True; statement 2 is a correct explanation for statement 1.

2.
Statement 1 is True, statement 2 is True; statement 2 is not a correct explanation for statement 1.

3.
Statement 1 is True, statement 2 is False.

4.
Statement 1 is False, statement 2 is True.

-1 out of 3 marks
Correct Answer: 1
Solution:
Ans: (1)

9 Answers

1
sriraghav ·

In stmt 2: shd it not be " B is of order n x m"??

1
sriraghav ·

some one answer this one..

1
The Scorpion ·

not necessarily... only required condition is dat "no. of rows in second matrix must b equal to no. of coloumns in first matrix... to multiply two matrices..."

well, u can also conclude lyk dis... AB=A => B is an identity matrix, and identity matrices are always square matrices... :)

1
sriraghav ·

so in stmt 2 : there can b any value in n x __ ....And it will bcome stmt 2 as wrong one....

1
sriraghav ·

coz stmt2 is not always true

1
The Scorpion ·

nope... see let me tell u clearly now...

dis is d basic step of multiplication...

(m x n).(n x p) = (m x p) ...... rite...!!!

now since RHS is A... and first matrix in LHS is also A, so both of them should have same order... i.e., (m x n)... hence p=n... which implies dat order of B must be (n x n)... implies it has to b a square matrix...

got it now... :)

11
Subash ·

The second statement is wrong i too answered it the same way

@mak

it is not true because for only the product to be defined the order of B can be nxp (p ≥1)

1
Optimus Prime ·

sriraghav how much did u get in the test?

1
The Scorpion ·

oh yeah... i'm sorry... i read statement 2 in ref. wid statement 1... so made dat blunder...

well, considering statement 2 individually, it's false... i agree... :)

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