Question

If `[2x4][{:(x),(-8):}]=O`, find the positive value of x.

Answer 1

The given matrix equation is `AB=O`, where A is a `(1xx2)` matrix and B is a `(2xx1)` matrix. So, AB is a `(1xx1)` matrix.
So, O is a `(1xx1)` matrix.
`:." "[2x4][{:(x),(-8):}]=[0]`
`implies" "2x^(2)-32=0implies2x^(2)=32`
`implies" "x^(2)=16impliesx=sqrt(16)=4.`
Hence, x=4.