- Adding and Subtracting Radicals
Definition: Radicals are expressions that include roots (like square roots). You can only add or subtract radicals that have the same index and radicand (the number inside the root).
Example:
- √2 + √2 = 2√2
- 3√5 - √5 = 2√5
Note: Non-like radicals cannot be combined, e.g.,
- √3 + √2 cannot be simplified further.
- Multiplying and Dividing Radicals
Multiplying Radicals: To multiply radicals, you multiply the coefficients and the radicands separately.
Example:
- √3 * √5 = √(3*5) = √15
- 2√2 * 3√2 = (23)(√2√2) = 6*2 = 12
Dividing Radicals: To divide radicals, divide the coefficients and the radicands separately.
Example:
- √8 / √2 = √(8/2) = √4 = 2
- 4√5 / 2√5 = (4/2)(√5/√5) = 2*1 = 2
- Evaluating Roots
Evaluating Square Roots: The square root of a number is a value that, when multiplied by itself, gives that number.
Example:
- √16 = 4
- √25 = 5
Higher Roots:
- The cube root of a number is a value that, when multiplied by itself three times, gives that number. For example,
- ∛27 = 3 (since 3 * 3 * 3 = 27)
- The fourth root of a number is a value that, when multiplied by itself four times, gives that number. For example,
- ∜16 = 2 (since 2 * 2 * 2 * 2 = 16)
- Products of Irrational Square Roots
When multiplying two irrational square roots, you may be able to simplify them.
Example:
- √2 * √8 = √(2*8) = √16 = 4
- √3 * √12 = √(3*12) = √36 = 6
- Identifying Roots
Identify roots by recognizing perfect squares or cubes:
• Perfect squares: Numbers like 1, 4, 9, 16, 25, etc., which are squares of integers (1², 2², 3², etc.).
• Perfect cubes: Numbers like 1, 8, 27, 64, 125, etc., which are cubes of integers (1³, 2³, 3³, etc.).
Example:
• Identify if 36 is a perfect square: Yes, since 6 times 6 = 36
• Identify if 50 is a perfect square: No.
• Identify if 64 is a perfect cube: Yes, since 4 times 4 times 4 = 64
• Identify if 30 is a perfect cube: No.
- Estimating Values of Expressions with π (Pi)
Using Approximation: The value of π is approximately \( 3.14 \). Use this to estimate expressions involving π.
Example:
• Estimate the circumference of a circle with a radius of 5:
- Circumference = 2πr = 2 * 3.14 * 5 ≈ 31.4
• Estimate the area of a circle with a radius of 3: - Area = πr² = 3.14 * (3²) = 3.14 * 9 ≈ 28.26