blabla
f ′ ( x 1 ) = lim Δ x → 0 f ( x 1 + Δ x ) − f ( x 1 ) Δ x {\displaystyle f\!\,'(x_{1})=\lim _{\Delta x\to 0}{\frac {f(x_{1}+\Delta x)-f(x_{1})}{\Delta x}}}
weiterso
y = f ( x 1 ) = a {\displaystyle y=f(x_{1})=a} const.
y = f ( x 1 ) = x {\displaystyle y=f(x_{1})=x}
