the locus of the vertex !
Many students learn that the effect of varying the parameter a in the expression
ax^2 + bx + c is to make the opening of the graph of the parabola either wider or
narrower. Similarly many students learn that the effect of varying the parameter c
is to raise or lower the graph.
What is the effect of varying the parameter b ? You can use this environment to explore the
question.
You can test your conjectures about the locus of the vertex by checking the "trial locus" box.
Challenge - for fixed values of a and c , write an expression for the curve traced out
by the vertex of parabola ax^2 + bx + c as you vary the parameter b .