Hello,
So i am now at point 4 in the Alu Worksheet where f(x) = x

The problem arrises at F. where it is false and so i have to do the first multiplication.
So i am multiplying 0100 x 1111 = 0111100.This is a signed number so 0 goes away but indicates that the number is positive so we have 111100 right?

Also this is a confusing answer because it has more bits than 4 and because i know we work in 4bit system i wonder if this answer is correct.
The previous exercises always got me no=f(x,y) but this doesn't.

When f=0 the ALU does binary AND which uses the symbol '&' in the worksheet.
When f=1 the ALU does arithmetic ADD which uses the symbol '+' in the worksheet.

The symbol '|' means binary OR. '+' in this worksheet always means ADD.