Complete Square 7C7F11
1. **State the problem:** Express the quadratic expression $4x^2 - 12x + 13$ in the form $(2x + a)^2 + b$, where $a$ and $b$ are constants.
2. **Recall the formula:** To write a quadratic in the form $(mx + a)^2 + b$, we complete the square. The general approach is:
$$ax^2 + bx + c = a\left(x^2 + \frac{b}{a}x\right) + c$$
Then complete the square inside the parentheses.
3. **Apply to our problem:**
Given $4x^2 - 12x + 13$, factor out 4 from the first two terms:
$$4x^2 - 12x + 13 = 4\left(x^2 - 3x\right) + 13$$
4. **Complete the square inside the parentheses:**
Take half of the coefficient of $x$, which is $-3$, so half is $-\frac{3}{2}$.
Square it: $$\left(-\frac{3}{2}\right)^2 = \frac{9}{4}$$
Add and subtract this inside the parentheses:
$$4\left(x^2 - 3x + \frac{9}{4} - \frac{9}{4}\right) + 13 = 4\left(\left(x - \frac{3}{2}\right)^2 - \frac{9}{4}\right) + 13$$
5. **Simplify:**
Distribute 4:
$$4\left(x - \frac{3}{2}\right)^2 - 4 \times \frac{9}{4} + 13 = 4\left(x - \frac{3}{2}\right)^2 - 9 + 13$$
Combine constants:
$$4\left(x - \frac{3}{2}\right)^2 + 4$$
6. **Rewrite in the desired form:**
Since $4\left(x - \frac{3}{2}\right)^2 = (2x - 3)^2$, the expression is:
$$(2x - 3)^2 + 4$$
**Final answer:**
$$4x^2 - 12x + 13 = (2x - 3)^2 + 4$$