The surface area of a sphere having a diameter of 8 inches is:

or

Step-by-step explanation:

The surface area of a sphere is calculated by the following formula

Where r is the radius of the sphere

In this case we know that the diameter d of the sphere is

So the radius r is:

So the surface area of the sphere is:

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for

tip $2.90

total $17.40