Suppose you deposited $900 into an account that earns 4% simple annual interest. find the balance of the account after 6 months

Balance after 6 months would be  900*(900+2%). You just need to evaluate it then you will get the answer. btw 2% comes from 4% because it's half of the year.

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.