1. **State the problem:** We are given the function $f(x) = x^2 + 25$ and need to find the value of $x$ such that $f(x) = 29$. 2. **Write the equation:** Set $f(x)$ equal to 29: $$x^2 + 25 = 29$$ 3. **Isolate $x^2$:** Subtract 25 from both sides: $$x^2 + \cancel{25} - \cancel{25} = 29 - 25$$ $$x^2 = 4$$ 4. **Solve for $x$:** Take the square root of both sides: $$x = \pm \sqrt{4}$$ $$x = \pm 2$$ 5. **Interpret the result:** The values of $x$ that satisfy $f(x) = 29$ are $x = 2$ and $x = -2$. 6. **Choose the best answer from the options:** The options are A: -2, B: 4, C: 5, D: 8. Since $x = -2$ is one of the solutions, the best answer is **A -2**. **Final answer:** $\boxed{-2}$