Final answer:
Without the exact radical expressions related to the values of a=9 and b=4, it is not possible to provide a specific evaluation. However, the student mentioned radical expressions seem to refer to roots calculated using the quadratic formula for quadratic equations of the form at² + bt + c = 0.
Step-by-step explanation:
The student's question involves evaluating radical expressions for given values of a and b. The provided information seems to be mismatched with different values of a, b, and c that pertain to various quadratic equations. Hence, we cannot directly answer the student's question without the specific radical expressions they're referring to.
However, if we assume the student's radical expressions are related to the quadratic formula, which is the solution to the quadratic equation of the form at² + bt + c = 0, then for specific values of a, b, and c, the quadratic formula is used for finding the values of t that satisfy the given equation.
To apply the quadratic formula, which is -b ± √(b² - 4ac) / 2a, we substitute the known values of a, b, and c into the formula. This would give us the roots of the equation, which can be real or complex numbers.
Without the exact radical expressions, we are unable to carry out any specific evaluations for a = 9 and b = 4. If the student provides the correct expressions, a solution can be offered accordingly.