$\textcolor{#3333CC}{f(x,y)=}$

f(x, y) = ((x + 1) * ℯ^(y))
f'_{x} = Derivative(f, x)
f'_{y} = Derivative(f, y)
f': {{f'_{x}, f'_{y}}}
f''_{x1} = Derivative(f'_{x}, x)
f''_{y1} = Derivative(f'_{y}, x)
f''_{x2} = Derivative(f'_{x}, y)
f''_{y2} = Derivative(f'_{y}, y)
f'': {{f''_{x1}, f''_{y1}}, {f''_{x2}, f''_{y2}}}
X_{0} = PointIn(xOyPlane)
f'_{x0}: {{f'_{x}(X_{0}), f'_{y}(X_{0})}}
f''_{x0}: {{f''_{x1}(X_{0}), f''_{y1}(X_{0})}, {f''_{x2}(X_{0}), f''_{y2}(X_{0})}}
Δ_{x}: {{x - x(X_{0})}, {y - y(X_{0})}}
T: f(X_{0}) + (f'_{x0} * Δ_{x}) + (((1 / 2 * Transpose[Δ_{x}]) * f''_{x0}) * Δ_{x})
T_{f}(x, y) = If[x(X_{0}) - 2 ≤ x ≤ x(X_{0}) + 2 ∧ y(X_{0}) - 2 ≤ y ≤ y(X_{0}) + 2, Element[T, 1, 1]]
F: X_{0} + (0, 0, f(X_{0}))
g = Segment(X_{0}, F)
Eingabefeld1 = Textfield(f)
textGrad: "\text{grad }f(x,y)=" + (LaTeX[f']) + ""
textHesse: "H_{f}(x,y)=" + (LaTeX[f'']) + ""