asked 218k views
1 vote
Let A be an m×n matrix and let w be a vector in Rⁿ that satisfies the equation Ax = 0. Show that for any scalar c, the vector cw also satisfies Ax = 0.

asked
User Elia
by
8.0k points

1 Answer

5 votes

To show that for any scalar c, the vector cw also satisfies the equation Ax = 0, we need to demonstrate that multiplying the matrix A by the vector cw results in a zero vector.

Given that Ax = 0, we know that multiplying the matrix A by the vector x yields a zero vector. We can express this as:

A * x = 0

Now, let's consider the vector cw, where c is a scalar. Multiplying the matrix A by cw gives:

A * (cw)

Using the properties of matrix multiplication and scalar multiplication, we have:

A * (cw) = (Ac) * w

Since Ac is the result of multiplying the matrix A by the scalar c, it is still a matrix. Therefore, we can rewrite the expression as:

(Ac) * w

Now, if we substitute cw with its equivalent expression (Ac) * w, we have:

(Ac) * w = (A * c) * w

Again, using the properties of matrix multiplication and scalar multiplication, we can write:

(A * c) * w = c * (A * w)

Since Ax = 0, we know that A * x = 0. Therefore, substituting x with w, we have:

c * (A * w) = c * 0

And finally:

c * 0 = 0

This shows that multiplying the matrix A by the vector cw results in a zero vector. Hence, for any scalar c, the vector cw also satisfies the equation Ax = 0.

answered
User Mihado
by
8.3k points