The horizontal asymptote is the limit of the temperature as time goes to infinity.
If we ignore the constant in the denominator, then
![T = (4t)/(t^2) = (4)/(t)](https://img.qammunity.org/2019/formulas/mathematics/college/6k80592ro0v4no9lawhjmna1ckkntnslkn.png)
And the limit as t-> infinity is 0
![\lim_(t \to \infty) (4)/(t) = 0](https://img.qammunity.org/2019/formulas/mathematics/college/ws054mtfc5h8am169gwsrvntuuk8vra8ii.png)
This means the temperature will decrease over time approaching 98.6 in the long run.