Phu

@Steve: what about this sequence? 64,96,144,216,324

U must connect 'total internal reflection to occur' with the place it takes place which is described in the 1st paragraph in order not to misunderstand the problem. The solution is really easy to find then.

Hahah so easy took only 1 calculation consisting of 2 operation yeah yeah

log(5)(5x-4) = log(√5)(2-x) = log(5)[(2-x)^2] 5x-4=x^2-4x+4