3x^3-18x^2-165x=0
Since we are given the solutions, we can rewrite them.
x=-5 is (x+5)
x=11 is (x-11)
x=0 is just x
Now we can write our equation:
3x(x+5)(x-11)=0
*3 comes from the a being 3
Now we multiply, Iād recommend starting by using FOIL on the last two first and getting;
3x(x^2-6x-55)=0
Then distribute the 3x:
3x^3-18x^2-165x=0
