Find a degree 3 polynomial that has zeros − 1 , 4 and 5 and in which the coefficient of x 2 is − 24 .

Y = (x + 1)(x - 4)(x - 5) 
You have to expand this by removing the brackets.When you do. You get
y = x^3 - 8x^2 + 11x + 20
If you multiply the entire right side by 3 you will get an x^2 term of - 24 and that will not affect the roots at all, because it is a constant that can be factored out before finding the roots.

y = 3(x^3 - 8x^2 + 11x + 20)
y = 3x^3 - 24x^2 + 33x + 60 <<<< answer.