On a particular day in Salt Lake, UT, the temperature was given by -t^2 + 12t + 50 where t is the time in hours past noon. What is the largest t value at which the temperature was exactly 85 degrees?
To solve this, we can set the equation up as \(-t^2+12t+50=85\).
Solving this equation we get:
\(-(t^2-12t+35)=0 \)
\(-(t-7)(t-5)=0\)
To get
\(t=7, t=5\)
The largest t value will be 7