From the given recurrence, it follows that

and so on down to the first term,

(Notice how the exponent on the 2 and the subscript of <em>a</em> in the first term add up to <em>n</em> + 1.)
Denote the remaining sum by <em>S</em> ; then

Multiply both sides by 2 :

Subtract 2<em>S</em> from <em>S</em> to get

So, we end up with

Answer:
52
Step-by-step explanation:
A cubical box without a top is 4 cm on each edge containing 64 identical 1 cm cubes.
We have to find the number of small cubes that actually touch the box.
Now, there are 4 layers of 16 cubes from bottom to top.
In the bottom-most layer, all the 16 small cubes will touch the bottom of the large cube.
Again, from the top three layers, only the outer small cubes will touch the sides of the large cube.
So, there are 12 small cubes in each top three layers that will touch the large cube.
Hence, in total there will be (16 + 12 ×3) = 52 small cubes that actually touch the large cube box. (Answer)
Answer:
3.5 lbs.
Step-by-step explanation:
1/4 of the water is dumped, meaning that is 3 lbs. 1/4 is 3 lbs. 3x4 is 12. 15.5 - 12 = 3
Answer:
They are b and c.
Step-by-step explanation:
Let's simplify each expression:
a. b+2 (b+2b)
= b + 2b + 4b = 7b.
b. 3b + b = 4b.
c. 2(2b) = 2 * 2b = 4b.