Question

if each edge of a cube is tribled (a) how many times will its surface area increase (b) how many times will its volume increase​

Answer 1

Suface area of cube is 6a^2. On tripling the edge, it will be 6(3a) ^2, which is equal to 54 a^2. Hence it becomes 9 times.

Volume is a^3. It will become (3a) ^3, which is equal to 27a^3. Hence it will become 27 times.