Sqrt Complex
1. The problem is to evaluate the expression $\sqrt{4 + 3i}$.
2. To find the square root of a complex number, we assume it can be written as $a + bi$ where $a$ and $b$ are real numbers.
3. Square $a + bi$ and set it equal to $4 + 3i$:
$$ (a + bi)^2 = a^2 + 2abi + (bi)^2 = a^2 - b^2 + 2abi = 4 + 3i $$
4. Equate the real and imaginary parts:
Real part: $a^2 - b^2 = 4$
Imaginary part: $2ab = 3$
5. From the imaginary part, solve for $b$:
$$ b = \frac{3}{2a} $$
6. Substitute $b$ into the real part equation:
$$ a^2 - \left( \frac{3}{2a} \right)^2 = 4 $$
$$ a^2 - \frac{9}{4a^2} = 4 $$
7. Multiply both sides by $4a^2$ to clear the denominator:
$$ 4a^4 - 9 = 16a^2 $$
8. Rearranged:
$$ 4a^4 - 16a^2 - 9 = 0 $$
9. Let $x = a^2$, rewrite as:
$$ 4x^2 - 16x - 9 = 0 $$
10. Solve this quadratic equation:
$$ x = \frac{16 \pm \sqrt{16^2 - 4 \cdot 4 \cdot (-9)}}{2 \cdot 4} = \frac{16 \pm \sqrt{256 + 144}}{8} = \frac{16 \pm \sqrt{400}}{8} = \frac{16 \pm 20}{8} $$
11. Thus, two solutions for $x$:
$$ x_1 = \frac{16 + 20}{8} = \frac{36}{8} = 4.5 $$
$$ x_2 = \frac{16 - 20}{8} = \frac{-4}{8} = -0.5 \text{ (discard negative since } a^2 \geq 0) $$
12. So, $a^2 = 4.5$, hence $a = \pm \sqrt{4.5} = \pm \frac{3}{\sqrt{2}}$.
13. Find $b$ using $b = \frac{3}{2a}$:
If $a = \frac{3}{\sqrt{2}}$,
$$ b = \frac{3}{2 \cdot \frac{3}{\sqrt{2}}} = \frac{3}{\frac{6}{\sqrt{2}}} = \frac{3 \sqrt{2}}{6} = \frac{\sqrt{2}}{2} $$
If $a = -\frac{3}{\sqrt{2}}$,
$$ b = \frac{3}{2 \cdot -\frac{3}{\sqrt{2}}} = -\frac{\sqrt{2}}{2} $$
14. Therefore, the square roots are:
$$ \sqrt{4+3i} = \pm \left( \frac{3}{\sqrt{2}} + \frac{\sqrt{2}}{2} i \right) $$
15. Simplify $a$ by rationalizing denominator:
$$ \frac{3}{\sqrt{2}} = \frac{3\sqrt{2}}{2} $$
Final answer:
$$ \boxed{ \pm \left( \frac{3\sqrt{2}}{2} + \frac{\sqrt{2}}{2} i \right) } $$