For some real number xxx, x2≠x\sqrt{x^2} \neq xx2=x. Therefore xxx is :
A negative number would work here. Suppose x=−1x=-1x=−1: x2≠x \sqrt{x^2} \neq x x2=x (−1)2≠−1 \sqrt{(-1)^2} \neq -1 (−1)2=−1 1≠−1 \sqrt{1} \neq -1 1=−1 1≠−1 ✓ 1 \neq -1 \checkmark 1=−1 ✓