Answer:

Step-by-step explanation:
1) In this question we've been given "a", the leading coefficient. and two roots:

2) There's a theorem, called the Irrational Theorem Root that states:
If one root is in this form
then its conjugate
. is also a root of this polynomial.
Therefore

3) So, applying this Theorem we can rewrite the equation, by factoring. Remembering that x is the root. Since the question wants it in this expanded form then:

(4 times 4 times 5) + (5 times 10 times 8) = 480 in cubed.
In rectangular form, we have the coordinates 
First, incorporate the 5 into the 2/3 fraction by multiplying the 5 by the 3 and then adding that quantity by the 2, which now makes the fraction:
17/3
Now set it up with the equation:
r/6 = 17/3
r/6×3 = 17/3×3
r/3 = 17
r/3×3 = 17×3
r = 51