Simple question about signed integer multiplication
Your answer is nearly right.
So x is an unsigned negative value of k bits. The smalles possible value of x is representet by the 2's Complement number 1000....0. If you multiply this number by 2 (or logical shifting it by 1, which is equivalent) you end up with the number 0000...0 which is 0. And therefore (x*2)&lt;0 is false.