Let B = age on Ben
and age of Ishaan =I
B =4I
B = 6+I
Gives 6+I = 4I
6 = 3I
I =2 years and B = 4x2 = 8years
Age of Ishaan = 2 years
Multiply the number of days by the amount of time you save each week.
has critical points where the derivative is 0:
The second derivative is
and , which indicates a local minimum at with a value of .
At the endpoints of [-2, 2], we have and , so that has an absolute minimum of and an absolute maximum of on [-2, 2].
So we have
If dimensions are multiplied by 3 then area is multiplied by 3^2