Sketch each of these curves and indicate clearly the axis intercepts.

a. y = |(x + 1) (x – 2) (x – 3)|

b. y = |2(5 – 2x) (x + 1) (x + 2)|

c. y = |x(9 – x²)|

d. y = |3(x – 1)² (x + 1)|