四次函數的圖形
Author: 王麗閔

u = Vector((x(Corner[1]), 0), (x(Corner[3]), 0))
v = Vector((0, y(Corner[1])), (0, y(Corner[3])))
a = -1.4 (slider from -5 to 5, step 0.1)
b = -1.4 (slider from -5 to 5, step 0.1)
c = 4.3 (slider from -5 to 5, step 0.1)
d = 0.6 (slider from -5 to 5, step 0.1)
e = 2.3 (slider from -5 to 5, step 0.1)
f(x) = a * x^(4) + b * x^(3) + c * x^(2) + d * x + e
A, B = TurningPoint(f)
C, D, E = Extremum(f)
text2: "當x=" + (LaTeX[x(C)]) + "時有極值" + (LaTeX[y(C)]) + ""
text1: "當x=" + (LaTeX[x(D)]) + " 時有極值" + (LaTeX[y(D)]) + ""
text3: "當x=" + (LaTeX[x(E)]) + "時有極值" + (LaTeX[y(E)]) + ""