[tex]y=a^x\\\\if\ a>1,\ then\ the\ graph\ is\ increase\ and\ has\ positives\ values\ of\ y\\\\if\ a\in(0,\ 1),\ then\ the\ graph\ is\ decrease\ and\ has\ positives\ values\ of\ y\\\\y=-a^x\\\\if\ a\in(0,\ 1),\ then\ the\ graph\ is\ increase\ and\ has\ negatives\ values\ of\ y\\\\if\ a>1,\ then\ the\ graph\ is\ decrease\ and\ has\ negatives\ values\ of\ y[/tex]
[tex]f(x)+n\to translate\ the\ graph\ n\ units\ up\\\\f(x)-n\to translate\ the\ graph\ n\ units\ down\\\\[/tex]
[tex]\text{We have the decrease graph with negatives values of y}.\\\\\text{Therefore your answer is}:\ \boxed{y=-4^x+3}[/tex]
