I need an explanation for the problem 4v2=-12v-9. I don't understand why it factors into 4v+3 and 4v+3

Factor the monomial completely 42a3b3

What happens to the area as the sliders are adjusted? what do you think the formula for the area of a triangle is divided by 2?

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.