In: Math
10. Assume k is a scalar and A is a m × n matrix. Show that if kA = 0 then either k = 0 or A = 0m x n
Here, k is a scalar and A is a mxn matrix.
Then, A =
is a mxn matrix.
Now, kA = k
=
Given kA = O
i.e.,
=
i.e., kaij = 0, where 1
i
m and 1
j
n.
which implies either k = 0 or aij = 0.
[Since we know that product of two numbers is 0 implies that one of them must be 0]
Now, aij = 0 for 1
i
m, 1
j
n implies
=
i.e., A =
.
Therefore, if kA = 0 then either k = 0 or A = 0mxn.