Convert boolean expression to pos then nor only

Question

I'm trying to convert a + xb + xyz to POS then to nor only.

First I got, a'(x' + b')(x' + y' + z') by using the duality rule but then I get confused after that.

Thanks.

Answer 1

You may expand the expression you got:

a'(x'+ b')(x' + y' + z') = a'x' + a'x'y' + a'x'z' + a'b'x' + a'b'y' + a'b'z'