Answer:
Part a. 1400 unit²
Part b 1240 unit²
Part c 1333.33 unit²
Step-by-step explanation:
The given function is 20·x - x²
Part a.
The dimensions of the five rectangles are;
20 × 20 + 20 × 18 + 20 × 16 + 20 × 10 + 20 × 6 = 1400 unit²
Part b.
The dimensions of the ten rectangles are;
10×20 + 10×18 + 10×16 + 10×16 + 10×14 + 10×12 + 10 × 10 + 10 × 8 + 10 × 6 + 10 ×4 = 1240 unit²
Part c.
To find the area with an infinite number of rectangles, we can use limits similar to integration;
Which gives;
10×20^2 - (20^3)/3 = 4000/3 = 1333.3333