Chapter 9 - Quadratic Functions and Equations - Concept Byte - Collecting Quadratic Data - Page 547: 1

The area is the product of two numbers (not the sum) and thus cannot be modeled by a linear function. There is no numerical base that we are using an exponent, so exponential functions cannot be used.

$A = l*w$ $perimeter = 2*l+2*w$ $40 = 2*l+2*w$ $40=2*(l+w)$ $40/2=2*(l+w)/2$ $20 = l+w$ $20-w=l+w-w$ $20-w = l$ $A = l*w$ $A = (20-w)*w$ $A = 20w-w^2$