Final answer:
The provided values for q, r, and s are possibly meant for substitution into a specific expression, which was not given. Nevertheless, information was shared about solving quadratic equations with the provided constants, and q typically represents the heat exchanged in a chemical reaction. The line of best fit was given for a potential statistics problem.
Step-by-step explanation:
The student's question does not provide the specific expression to evaluate, but we were provided with the values for q, r, and s: q = 4, r = -3, and s = -20.4. However, the rest of the information given seems to relate to various quadratic equations and a statistics problem involving a line of best fit. To evaluate a quadratic expression of the form at² + bt + c = 0, one would substitute the values into the quadratic formula, x = (-b ± √(b² - 4ac)) / 2a, to find the solutions for t. If we were evaluating the quadratic equation where a = 4.90, b = -14.3, and c = -20.0, the solutions for t would be calculated as follows:
Using the quadratic formula: t = (-(-14.3) ± √((-14.3)² - 4 × 4.90 × (-20.0))) / (2 × 4.90)
Furthermore, if we were to calculate the value of q for a chemical reaction and explain the meaning of its arithmetic sign, we would need more context about the reaction. Typically q represents the heat exchanged in a reaction, and its sign indicates whether the reaction is absorbing (+) or releasing (-) heat.
As for the linear regression question, using the line of best fit î = -173.51 + 4.83x, we can predict the final exam score given a third exam score. The value of r (0.663), in this case, shows a moderate positive correlation between the variables.