x=1 ⇒ x^2=1

<Direct method>

1^2 = 1, therefore the proposition is true.

<Contraposition method>

x^2 != 1 ⇒ x != 1

x^2 != 1 ⇔ x != ±1, thus the proposition is true.

<Contradiction method>

Let x=1 and x^2 != 1.

x^2 != 1 ⇔ x != ±1, thus x=1 and x!=1, which is contradictory.

Therefore the proposition is true.