Acarpet installer charges a flat rate of $40, plus $1.50 per square foot for labor. so, the total cost for labor depends on the amount of carpet installed. the relationship between the total cost for labor and the amount of carpet installed is

 Proportional

Step-by-step explanation:

Given : A flat rate charged by the carpet installer = $40

On addition to that , he charges $1.50 per square foot for labor.

Then , Total cost of carpet= Fixed rate of $40 +  $1.50 per square foot for labor.

Let x be the area of the carpet in square feet.

Then, the total cost ( in $)= 40 +1.50x , which is a linear function with slope 1.50.

According to the definition of linear function , we have

A linear function is in the form  of , it shows that the relationship between x and y is proportional.

That means ,  The relationship between the total cost for labor and the amount of carpet installed is proportional.

x² + 3x + 7 = 0       [ax² + bx + c]

a = 1

b = 3

c = 7

quadratic formula:

    (+/- is this ±)

plug in the numbers into the variables

your answer is a