Which of the following has a graph that is a straight line?

a. equation 1: y = 4x3 + 6

b. equation 2: y = 5x − 4.5

c. equation 3: y2 = x − 1

d. equation 4: y = 2x2 + 6

Aclothing designer is selecting models to walk the runway for her fashion show. the clothes she designed require each model’s height to be no more than y inches from 5 feet 10 inches, or 70 inches. which graph could be used to determine the possible variance levels that would result in an acceptable height, x?