How to right a function for a story problem

Which expression is equivalent to 2x^2+7x+4?

The lengths of nails produced in a factory are normally distributed with a mean of 4.91 centimeters and a standard deviation of 0.05 centimeters. find the two lengths that separate the top 4% and the bottom 4%. these lengths could serve as limits used to identify which nails should be rejected. round your answer to the nearest hundredth, if necessary.

Write the equation for the parabola that has x− intercepts (−2,0) and (4,0) and y− intercept (0,4).