In function evaluation, the number inside the parentheses is the input, and the question asks for the output. Replace every in the rule with that input, or define the rule in Desmos and evaluate it on the next line. The square-root symbol gives the nonnegative root, not both numbers that square to the same value.
Hints
- Hint 1
In function notation, the number in parentheses is the input, not a number you multiply by the function's name. For , what number replaces in the given rule?
- Hint 2
A square root is the nonnegative number that squares to the value underneath the radical. After you replace and add, what number is under the radical?
Step-by-step
Substitute, then evaluate in Desmos
Step 1Put the input into the rule
The in is the input to the function, a rule that gives an output. Replace with inside the rule:
- Step 2
Read the output
Type in Desmos, then type on the next line. Desmos shows . Since and , the square root of is . It isn't : the square-root symbol gives the nonnegative root. So the value of is . Choice B.