text: in the exponential decay equation y=3( 0.25) ^ x , is there a value of x that makes y less than 0? can some please tell me the ansswer and explain. no.  a number to a negative power becomes one over that number.  for example 2 to the -2 power becomes one over four.  first you square two then put it in the denominator as a positive.  any number you plug in for x will still yield a value of y greater than 0.