Question:
What is f(-3) if f(x) = x² + 5?
What is f(-3) if f(x) = x² + 5?
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A common mistake is incorrectly handling the negative sign when squaring. Remember that \((-a)^2 = (-a) \times (-a) = a^2\). Always use parentheses when substituting a negative value to avoid errors, especially with calculators.
Updated On: Oct 3, 2025
- -14
- 4
- 15
- 14
- -4
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The Correct Option is D
Solution and Explanation
Step 1: Understanding the Concept:
This question asks to evaluate a function, \(f(x)\), at a specific value of \(x\). To find \(f(-3)\), we need to substitute \(-3\) for every \(x\) in the expression for \(f(x)\).
Step 2: Detailed Explanation:
The given function is \(f(x) = x^2 + 5\).
We need to find the value of \(f(-3)\).
Substitute \(x = -3\) into the function:
\[ f(-3) = (-3)^2 + 5 \] When squaring a negative number, the result is positive.
\[ f(-3) = 9 + 5 \] Now, perform the addition.
\[ f(-3) = 14 \] Step 3: Final Answer:
The value of \(f(-3)\) is 14.
This question asks to evaluate a function, \(f(x)\), at a specific value of \(x\). To find \(f(-3)\), we need to substitute \(-3\) for every \(x\) in the expression for \(f(x)\).
Step 2: Detailed Explanation:
The given function is \(f(x) = x^2 + 5\).
We need to find the value of \(f(-3)\).
Substitute \(x = -3\) into the function:
\[ f(-3) = (-3)^2 + 5 \] When squaring a negative number, the result is positive.
\[ f(-3) = 9 + 5 \] Now, perform the addition.
\[ f(-3) = 14 \] Step 3: Final Answer:
The value of \(f(-3)\) is 14.
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