a = 5 (slider from -5 to 5, step 0.1)
h = 3.1 (slider from -5 to 5, step 0.1)
k = 0.1 (slider from -5 to 5, step 0.1)
c: y = a * (x - h)^(2) + k
texte1: "y=" + a + "(x-" + h + ")²+" + k + ""