Question

The surface area of a rectangular prism is 150 cm². If all the sides are tripled, what will the new surface area be?

Answer 1

2ab + 2bc + 2ac is the formula for surface area. So the surface area of the new cube would be 2(3a)(3b) + 2(3b)(3c) + 2(3a)(3c) --> 18ab + 18bc + 18ac --> 9(2ab + 2bc + 2ac).
If the initial was 150, the tripled surface area would be 9 times that, or 1350 cm^2.