Answer:
100 and 200
Explanation:
Let the first number be 'a' and the second number be 'b'. If the sum of the first and twice the second is 400 then;
a+2b = 400 ....
From the equation above, a = 400 - 2b ... 2
If the product of the numbers is a maximum then;
ab = (400-2b)b
let f(b) be the product of the function.
f(b) = (400-2b)b
f(b) = 400b-2b²
For the product to be at the maximum then f'(b) must be equal to zero i.e f'(b) = 0
f'(b)= 400-4b = 0
400-4b = 0
400 = 4b
b = 400/4
b = 100
Substituting b= 100 into the equation a = 400 - 2b to get a;
a = 400 - 2(100)
a = 400 - 200
a = 200
The two positive integers are 100 and 200.