Which of the following is the value of x^2 + 1/x^2 when x + 1/x = 5?

$\left( x + \dfrac{1}{x} \right)^2 = 5^2$

$x^2 + 2 + \dfrac{1}{x^2} = 25$

$x^2 + \dfrac{1}{x^2} = 23$