1. Upon performing a series of row operations, the matrix 2 1 ?
-1 3 ?
becomes 1 0 2
0 1 -3
Find the two missing entries of the original matrix.
Please explain how
Solution
on performing row operation in order given below
R1-- R1+R2
1 4 x+y
-1 3 y
R2-- R2+R1
1 4 x+y
0 7 x+2y

2. R2-- (R2)/7
1 4 x+y
0 1 (x+2y)/7
R1--R1-4R2
1 0 3x/7-y/7
0 1 (x+2y)/7
so on equating
(3x-y)/7 = 2
(x+2y)/7 = -3
on solving above 2 eq
x= 1 &
y = -11
so missing entries (x,y) will be
(1,-11) ANS