I think the answer is .8282
Find a common denominator (12).
u/4=8/3
3u/12=32/12
Multiply each side by twelve to get rid of the denominator.
3u=32
u=1 2/3
1 and two-thirds equals 1.6666666 in decimal form, so the nearest tenth would be 1.7
Sum is

r=common ratio
a1=first term
it looks like 2^0=1 is the first term aka a1
it goes to the 9th term (2^9)
sub



When looking at expressions like this,, you need to remember that the square root of a negative number does not exist in the set of Real Numbers. This means that there is no way to simplify this expression,, making the correct answer to your question Undefined.
Let me know if you have any further questions.
:)