The function is (1)/((3^(x^2+1)) for x is greater than or equal to zero and

5x + 3 for x is less than 0.

I understand the range of 5x + 3 under these circumstances is y

is less than or equal to 3 (and this is also the range for the entire piecewise function). I don't understand how to find the range of the first part of the piecewise function with teh fractional exponent. My book doesn't explain it well.