Suppose our roots are [a, b, c]. We want a polynomial which is zero when x is any of these values. The trivial polynomial x-a is zero when x=a, so the product (x-a)(x-b)(x-c) will do the job. We can use a c x to write this in a more familiar form.
1: 34 x - 24 x^3 1: [1.19023, -1.19023, 0] . . r 2 a P x RET
1: [x - 1.19023, x + 1.19023, x] 1: (x - 1.19023) (x + 1.19023) x . . V M ' x-$ RET V R *
1: x^3 - 1.41666 x 1: 34 x - 24 x^3 . . a c x RET 24 n * a x
Sure enough, our answer (multiplied by a suitable constant) is the same as the original polynomial.