I need help on the following question:

1) The graph of a polynomial function shows x-axis intercepts at x = -1 and x = 3 and touches the x-axis (with a turning-point) at x = 2. The y-axis intercepts is at y = 24. Assuming the polynomial has degree four, write its equation in factorized form.

The equation i got is \(\displaystyle y = (x+1)(x-3)(x-2)^2.\)

This is incorrect, how did the book's answer get \(\displaystyle y = -2(x+1)(x-3)(x-2)^2\)

P.S