<span>f x=0 ==>x^4+400=0+400=400</span>
Answer:

Step-by-step explanation:
It is given that, the radius of a circle is 8 inches and we are to find the circumference of the circle.

To find the circumference of the circle we must know this formula first :

Where
- r is the radius of the circle.
- We'll take the value of π as 3.14
Now substituting the values in the formula :



Therefore,
- The circumference of the circle is 50.24 inches
-28 is equal to positive 28