c)
[tex]f(x) = \frac{1}{2}x^{2}-2\\\\f(x) = 0\\\\\frac{1}{2}x^{2}-2=0 \ \ \ |\cdot2\\\\x^{2}-4 = 0\\\\x^{2}-2^{2} = 0\\\\(x+2)(x-2) = 0\\\\x+2 = 0 \ \vee \ x-2 = 0\\\\x = -2 \ \vee x = 2\\\\\boxed{x \in \{-2,2\}}[/tex]
Wyjaśnienie:
[tex](a+b)(a-b) = a^{2}-b^{2}[/tex]
