Answer:
Dimensions of printed poster are
length is 32 cm
width is 48 cm
Step-by-step explanation:
Let's assume
length of printed poster is x cm
width of printed poster is y cm
now, we can find area of printed poster
so, area of printed poster is

we are given that area as 1536
so, we can set it to 1536

now, we can solve for y

now, we are given
The top and bottom margins of a poster are each 12 cm and the side margins are each 8 cm
so, total area of poster is


now, we can plug back y

now, we have to minimize A
so, we will find derivative

we can use product rule


now, we can simplify it

now, we can set it to 0
and then we can solve for x




Since, x is dimension
and dimension can never be negative
so, we will only consider positive value

now, we can solve for y


so, dimensions of printed poster are
length is 32 cm
width is 48 cm