It does not become the 1x1 matrix. The resultant shape of W^{T}X+b, which is denoted by Z, also depends on the shape of W. And the shape of W depends on the number of neurons in the hidden layer and the number of features.
It does not become the 1x1 matrix. The resultant shape of W^{T}X+b, which is denoted by Z, also depends on the shape of W. And the shape of W depends on the number of neurons in the hidden layer and the number of features.