3.3 Lösning 3c

\[\begin{array}{rcl} f(x) & = & x^4 \\ f'(x) & = & 4\,x^3 \\ f''(x) & = & 12\,x^2 \\ f'''(x) & = & 24\,x \end{array}\]

\[\begin{array}{rcl} f'(0) & = & 4 \cdot 0^3 \, = \, 4 \cdot 0 \, = \, 0 \\ f''(0) & = & 12 \cdot 0^2 \, = \, 12 \cdot 0 \, = \, 0 \\ f'''(0) & = & 24 \cdot 0 \, = \, 0 \end{array}\]

Enligt regeln om terasspunkter med högre derivator:

\( \, f\,'(0) \, = \, f\,''(0) \, = \, f\,'''(0) \, = \, 0 \quad \Longrightarrow \quad f(x) \, \) har ingen terasspunkt i \( \, x = 0 \, \).

Om \( \, f\,'''(0) \neq 0 \, \) hade \( \, x = 0 \, \) varit en terasspunkt.