Step-by-step explanation:
it maybe
8m= 36+20
m=56/8
=7 answer
Answer with Step-by-step explanation:
We are given that
A and B are matrix.
A.We know that for two square matrix A and B
Then, 
Therefore, it is true.
B. det A is the product of diagonal entries in A.
It is not true for all matrix.It is true for upper triangular matrix.
Hence, it is false.
C.

When is a factor of the characteristics polynomial of A then -5 is an eigenvalue of A not 5.
Hence, it is false.
D.An elementary row operation on A does not change the determinant.
It is true because when an elementary operation applied then the value of matrix A does not change.
The answer is to this question is a)strong positive...
Answer:
x= 2 and y = -4
Step-by-step explanation:
8x + 3y = 4 ---------------------------------(1)
-7x + 5y = -34 -----------------------------(2)
Multiply through equation (1) by 5 and multiply through equation(2) by 3
40x + 15y = 20 ----------------------------(3)
-21x + 15y =-102----------------------------(4)
Subtract equation (4) from equation (3)
61x = 122
Divide both-side of the equation by 61
61x/61 = 122/61
(At the left-hand side of the equation 61 will cancel-out 61 leaving us with just x, while at the left-hand side of the equation 122 will be divided by 61)
x = 122/61
x=2
Substitute x= 2 into equation (1)
8x + 3y = 4
8(2) + 3y = 4
16 + 3y = 4
Subtract 16 from both-side of the equation
16-16 + 3y = 4-16
3y = -12
Divide both-side of the equation by 3
3y/3 = -12/3
y = -4
x= 2 and y = -4