Please help me with this question

Me with this one question, and i'll upvote the brainliest answer

The roots of the function f(x) = x2 – 2x – 3 are shown. what is the missing number?

Arefrigeration system at your company uses temperature sensors fixed to read celsius (°c) values, but the system operators in your control room understand only the fahrenheit scale. you have been asked to make a fahrenheit (°f) label for the high temperature alarm, which is set to ring whenever the system temperature rises above –10°c. what fahrenheit value should you write on the label?