Answer
a) For x=1, we have $x^{2}=1=x$ and thus x=1 is a counterexample.
b) For $x= \sqrt 2$, we have $\sqrt 2^{2}=2$ and thus is $x=\sqrt 2$ a counterexample
c) For x=0, we have $|x|=|0|=0$ which is not greater than zero, and thus x=0 is a counterexample.
Work Step by Step
a) For x=1, we have $x^{2}=1=x$ and thus x=1 is a counterexample.
b) For $x= \sqrt 2$, we have $\sqrt 2^{2}=2$ and thus is $x=\sqrt 2$ a counterexample
c) For x=0, we have $|x|=|0|=0$ which is not greater than zero, and thus x=0 is a counterexample.