(5y^4-23y^3+24y^2-7)/(y-3)

Can you help me if I help you? the temperature of a room during an experiment can be modeled by the function f(x)=23.7 cos (Pi x /60) +18. Where f(x) is the temperature F degrees and x is the number is hours into the experiment. What is the lowest temperature the room reached during the expriement?
I got -5.7 F *

5 y^3-8y^2 with Remainder = -7

http://calc101.com/webMathematica/long-divide.jsp#topdoit

thanks