If a polynomial function f(x) has roots -9 and 7 - i, what must be a factor of f(x)? (x-(7+ i))
(x - (-7-i)
(x + (7 + i))
(x + (7-i))

Scores on the cognitive scale of the bayley-scales of infant and toddler development range from 1 to 19, with a standard deviation of 3. calculate the margin of error in estimating the true mean cognitive scale score, with 99% confidence, if there are 12 infants and toddlers in a sample.