1. **State the problem:** We are given a quadratic function $f(x) = ax^2 + bx + c$ and some values of $f(x)$ at specific $x$ values. We need to find $f(1)$.
2. **Write down the given values:**
$$
\begin{array}{c|ccccc}
x & 0 & 2 & 4 & 6 & 8 \\
f(x) & -3 & -3 & 5 & 21 & 45
\end{array}
$$
3. **Use the quadratic formula:**
$$f(x) = ax^2 + bx + c$$
We know $f(0) = c = -3$.
4. **Set up equations using other points:**
- At $x=2$: $$4a + 2b + c = -3$$
- At $x=4$: $$16a + 4b + c = 5$$
Substitute $c = -3$:
$$4a + 2b - 3 = -3 \implies 4a + 2b = 0$$
$$16a + 4b - 3 = 5 \implies 16a + 4b = 8$$
5. **Simplify and solve the system:**
Divide the first equation by 2:
$$2a + b = 0$$
Divide the second equation by 4:
$$4a + b = 2$$
Subtract the first from the second:
$$4a + b - (2a + b) = 2 - 0 \implies 2a = 2 \implies a = 1$$
Use $a=1$ in $2a + b = 0$:
$$2(1) + b = 0 \implies b = -2$$
6. **Write the quadratic function:**
$$f(x) = x^2 - 2x - 3$$
7. **Find $f(1)$:**
$$f(1) = 1^2 - 2(1) - 3 = 1 - 2 - 3 = -4$$
8. **Check with given answer:** The user states the answer is 12, so let's verify with other points to confirm.
Check $f(6)$:
$$f(6) = 36 - 12 - 3 = 21$$ which matches the table.
Check $f(8)$:
$$f(8) = 64 - 16 - 3 = 45$$ which matches the table.
Check $f(2)$:
$$f(2) = 4 - 4 - 3 = -3$$ matches the table.
Check $f(4)$:
$$f(4) = 16 - 8 - 3 = 5$$ matches the table.
So the function is correct, but $f(1) = -4$ not 12.
**Possibility:** The user answer 12 might be a mistake or from a different function.
**Final answer:**
$$\boxed{f(1) = -4}$$
Quadratic Value A36533
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