Help will give points

Factor -8x3-2x2-12x-3 by grouping what is the resulting expression?

Average acceleration: i have no idea how to do this.

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.