Sally is making a scale drawing of her apartment. • She drew a line measuring 1 1/2 inches to represent the 12-foot width of her living room.
• The length of her living room is 18 feet.

How long a line should Sally draw to represent the length of her living room?

A. 2 inches
B. 2 1/4 inches
C. 2 1/2 inches
D. 3 inches

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204