Question

20 is divided into two parts so that product of cube of one part and square of the other part is maximum. The parts are, respectively –

• A. 10, 10
• B. 16, 4
• C. 8, 12
• D. 12, 8

Answer 1

Answer: (D)

12, 8

Answer 2

x + y = 20

f(x, y) = x³. y² to be maximized so

f(x) = x³.(20 – x)²

$\frac{df(x)}{dx}$= 0 ̃ x = 12 so y = 8