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

9/100 is less because if we multiply 7/10 by 10 (to get an equivalent fraction with a denominator the same as the other fraction [100]) we get 70/100, which is way more than 9/100.
So, 7/10 is greater than 9/100
Hope this helps!
if the length is 8ft and the width is (7+x) then the area would be 56+8x, if x is unknown.
Hey there! I'm happy to help!
First, let's find the radius. The radius is half of the diameter.
8.4/2=4.2
Here's how to find the area of a circle.
Square the radius.
4.2²=17.64
And multiply by pi (3.14 in our case)
17.64(3.14)=55.3896
We round to the nearest tenth, giving us an area of 55.4 ft²
Have a wonderful day! :D