Surds 9B0466
1. The problem is to understand the topic of Surds, which are irrational roots that cannot be simplified to remove the root.
2. A surd is an expression containing a root, such as $\sqrt{2}$ or $\sqrt{3}$, that cannot be simplified to a rational number.
3. Important rules:
- $\sqrt{a} \times \sqrt{b} = \sqrt{ab}$
- $\frac{\sqrt{a}}{\sqrt{b}} = \sqrt{\frac{a}{b}}$
- You cannot add or subtract surds unless they have the same root part (like terms).
4. Example: Simplify $\sqrt{50}$.
- Factor 50 as $25 \times 2$.
- Use $\sqrt{50} = \sqrt{25 \times 2} = \sqrt{25} \times \sqrt{2} = 5\sqrt{2}$.
5. Example: Simplify $3\sqrt{8} + 2\sqrt{18}$.
- Simplify each surd:
$3\sqrt{8} = 3 \times \sqrt{4 \times 2} = 3 \times 2\sqrt{2} = 6\sqrt{2}$
$2\sqrt{18} = 2 \times \sqrt{9 \times 2} = 2 \times 3\sqrt{2} = 6\sqrt{2}$
- Add like surds: $6\sqrt{2} + 6\sqrt{2} = 12\sqrt{2}$.
6. Example: Rationalize the denominator of $\frac{5}{\sqrt{3}}$.
- Multiply numerator and denominator by $\sqrt{3}$:
$\frac{5}{\sqrt{3}} \times \frac{\sqrt{3}}{\sqrt{3}} = \frac{5\sqrt{3}}{3}$.
7. Surds are useful in exact answers where decimals are not precise.
Final answer examples:
- $\sqrt{50} = 5\sqrt{2}$
- $3\sqrt{8} + 2\sqrt{18} = 12\sqrt{2}$
- $\frac{5}{\sqrt{3}} = \frac{5\sqrt{3}}{3}$
This explanation covers the basics of surds with easy and tricky examples to help you understand.