a = 2 (slider from -5 to 5, step 1)
b = 0 (slider from -5 to 5, step 1)
c = 1 (slider from -5 to 5, step 1)
d = 4 (slider from -5 to 5, step 1)
texte1: "(" + a + "x + " + b + ")(" + c + "x + " + d + ")"
f = Expand((a * x + b) * (c * x + d))
texte2: "= " + f + ""
texte3: "= " + a + "x·" + c + "x + " + a + "x·" + d + " + " + b + "·" + c + "x + " + b + "·" + d + ""