1) The square root of an exponent is ½ of the exponent.
2) When you want two probabilities to occur (probabilities are ratios, such as 1:5 or one out of five or 1/5), multiply the two fractions, such as 1/5 times 1/4.
3) The square root of a negative number is plus or minus, the square root of the negative number as a positive number, paired with i, the notation for an imaginary number. √-25 = ±5i In math the symbol for √−1 is i for imaginary.