82.5 i believe because the radius is half of the diameter.
Given quadratic equation : 
Let us apply standard quadratic form 
We know, quadratic formula

a = 4
b = 2
c= -1
Now we plug in all the values in quadratic formula
.
<h3>The above one is the substitution of values of a,b,c in quadratic formula.</h3>
Answer:
8x(3x^2 +1)
Step-by-step explanation:
24x^3 + 8x
We can factor out 8x
8x(3x^2 +1)