 Hello and welcome to the session. In this session we discussed the following question which says three cubes of metal with edges 3 cm, 4 cm and 5 cm respectively are melted to form a single cube. Find the lateral surface area of the new cube formed. First we shall recall the formula for the volume and the lateral surface area of the cube with edge a-units. So it's volume that is volume of the cube with edge as a-units is given as a-tube cubic units. The lateral surface area of the cube with a-units as the edge is given as 4 a-square square units. This is the key idea for this question. Now we move on to the solution. Now the edge of cube one is given as 3 cm. The volume of cube one is equal to 3 cm cube and this is equal to 27 cm cube is the volume of the cube one whose edge is 3 cm. Next we have the edge of cube two is given as 4 cm then the volume of cube two is equal to 4 cm cube which is equal to 64 cm cube. Next the edge of cube three is given as 5 cm then the volume of cube three is equal to 5 cm cube and this is equal to 125 cm cube. So we have now got the volume of cube one as 27 cm cube, volume of cube two as 64 cm cube, volume of cube three as 125 cm cube. Now as in the question is given to us that three cubes are melted to form a single cube so now we have the volume of the new cube would be equal to the volume of cube one plus volume of cube two plus the volume of cube three that is this is equal to 27 plus 64 plus 125 cm cube is the volume of the new cube and this is equal to 216 cm cube is the volume of the new cube. Now suppose we take left the edge of the new cube be equal to a cm so we have a cube would be equal to 216 so this would give us a equal to 6 that is we have the edge of the new cube is equal to 6 cm. Now that we have got the edge of the new cube so we can easily find out the lateral surface area of the new cube and this is equal to 4 a square that is equal to 4 into 6 square which is equal to 144 cm square so the lateral surface area of the cube formed by melting the three given cubes is equal to 144 cm square so our final answer is 144 cm square so this completes the session hope you have understood the solution for this question.