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Powers and Indices

🎬 Video: Understanding Powers

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What are Powers in Math? (0:01)

A power is a way of writing repeated multiplication of the same number. They help express large and small numbers efficiently. In general, a power is written as:

$$ a^n $$

where:

  • $ a $ is the base. The base is the number being multiplied.
  • $ n $ is the index (exponent). The index (exponent) tells us how many times the base is multiplied by itself.

For example:
$$ 3^4 = 3 \times 3 \times 3 \times 3 $$

  • Here, 3 is the base.
  • 4 is the index, meaning 3 is multiplied by itself 4 times.
  • This is pronounced as “3 to the power of 4”.

What are Key Properties of Powers? (1:00)

Understanding the following properties will help you develop a strong grasp of exponents and indices.

  • The Base and Exponent Cannot Be Swapped.

$$ \text{For example, } 3^4 \neq 4^3 $$

  • Any Number to the Power of 1 Equals Itself.

$$ a^1 = a $$

  • Any Number (Except 0) to the Power of 0 Equals 1

$$ a^0 = 1 \quad \text{where } a \neq 0 $$

What are Square Numbers and Cube Numbers? (1:30)

Two of the most common powers are squares (index 2) and cubes (index 3).

Square Numbers:

  • A square number is a number that results from multiplying a whole number by itself.

$$ n^2 = n \times n $$

  • Common Square Numbers:

$$ 1^2 = 1, \quad 2^2 = 4, \quad 3^2 = 9, \quad 4^2 = 16, \quad 5^2 = 25, \quad 6^2 = 36 $$

Cube Numbers:

  • A cube number is a number that results from multiplying a whole number by itself three times.

$$ n^3 = n \times n \times n $$

  • Common Cube Numbers:

$$ 1^3 = 1, \quad 2^3 = 8, \quad 3^3 = 27, \quad 4^3 = 64, \quad 5^3 = 125 $$

Recognizing square and cube numbers helps you simplify expressions and solve equations more easily.

How to Use Exponents to Simplify Expressions? (2:05)

When multiplying the same number multiple times, you can use exponents (indices) to write the expression in a simplified form.

For example:

$$ 4 \times 3 \times 3 \times 4 \times 4 $$

We can group the same factors using the commutative and associative laws:

$$ (4 \times 4 \times 4) \times (3 \times 3) $$

Since each base is repeated, we can write it using exponents:

$$ 4^3 \times 3^2 $$

By using exponents for repeated multiplication, you make expressions easier to read, write, and work with.

How to Apply BIDMAS with Powers (Indices)? (2:30)

In BIDMAS (Brackets, Indices, Division, Multiplication, Addition, Subtraction),
indices (exponents) are calculated after brackets but before all basic operations.

Example 1: Brackets Before Indices
When an expression has brackets, evaluate the brackets first:

$$ (2 \times 5)^2 $$

  • Step 1: Solve inside the brackets:

$$ (10)^2 $$

  • Step 2: Apply the exponent:

$$ 100 $$

Example 2: Indices Before Multiplication
If there are no brackets around the multiplication, apply the exponent first:

$$ 2 \times 5^2 $$

  • Step 1: Evaluate the exponent first:

$$ 2 \times 25 $$

  • Step 2: Perform the multiplication:

$$ 50 $$

📂 Flashcards: Powers and Indices

🍪 Quiz: Practice with Indices and Exponents

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Powers

1 / 6

Q: What is the result of $10^0$?

2 / 6

Q: What is the value of $9^1$?

3 / 6

Q: Evaluate $(4^2) \times 3$.

4 / 6

Q: Calculate $5 \times 10^2$.

5 / 6

Q: Evaluate $(6^2) + (2^4)$.

6 / 6

Q: Simplify $(10^3) - (6 \times 5^2)$

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