Answer:
Part 3)
Part 4)
Step-by-step explanation:
Part 3) Calculate the total surface area of three 4 cm cubes
we know that
The surface area of a cube is equal to the area of its six square faces
so
The surface area of three cubes is equal to the area of its 18 square faces
where
b is the length side of the square face
In this problem
so
The surface area of three cubes is
substitute the given value
Part 4) How much surface area would be lost if you glued three 4-cm cubes together to make a rod that is three cubes long and one cube wide?
In this case the total surface area of the three glued 4-cm cubes is equal to the area of its 14 square faces
so
The surface area lost is equal to
substitute