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Number - Exponents, Powers, and Square Roots

Grade 7IB

Review the key concepts, formulae, and examples before starting your quiz.

πŸ”‘Concepts

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Definition of a Power: A power consists of a base and an exponent (also called an index). In the expression ana^n, aa is the base (the number being multiplied) and nn is the exponent (the number of times the base is multiplied by itself). Visually, think of the base as a large number and the exponent as a small superscript tucked into the top-right corner.

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Perfect Squares and Square Roots: A square number is the result of multiplying an integer by itself, visualized as a geometric square grid of dots. For example, 32=93^2 = 9 represents a 3Γ—33 \times 3 grid. The square root, represented by the radical symbol x\sqrt{x}, is the inverse operation that finds the side length of that square.

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Perfect Cubes and Cube Roots: A cube number is formed by multiplying a number by itself three times, such as a3=aΓ—aΓ—aa^3 = a \times a \times a. Visually, this represents the volume of a 3D cube with side length aa. The cube root x3\sqrt[3]{x} determines what value was multiplied three times to reach xx.

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Product of Powers Rule: When multiplying two powers with the same base, you keep the base and add the exponents. This can be visualized as expanding both terms into a long string of multiplications and then counting the total number of factors.

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Quotient of Powers Rule: When dividing two powers with the same base, you keep the base and subtract the exponent of the divisor from the exponent of the dividend. Visually, imagine writing the expression as a fraction and 'canceling out' pairs of the base from the numerator and denominator.

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Power of a Power Rule: To raise a power to another power, such as (am)n(a^m)^n, you multiply the exponents together. Visually, this represents a group of ama^m being repeated nn times in a larger structure.

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The Zero Exponent: Any non-zero base raised to the power of zero is equal to 11. For example, 50=15^0 = 1. This can be understood through patterns: as exponents decrease by 1, the resulting value is divided by the base until a1/aa^1 / a reaches 11 at the a0a^0 level.

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Identity Property: Any number raised to the power of 1 is the number itself. For example, a1=aa^1 = a. This is the simplest form of a power, indicating the base appears exactly once in the product.

πŸ“Formulae

amΓ—an=am+na^m \times a^n = a^{m+n}

aman=amβˆ’n\frac{a^m}{a^n} = a^{m-n}

(am)n=amΓ—n(a^m)^n = a^{m \times n}

a0=1 (where a≠0)a^0 = 1 \text{ (where } a \neq 0)

a1=aa^1 = a

(ab)n=anΓ—bn(ab)^n = a^n \times b^n

x2=x\sqrt{x^2} = x

x33=x\sqrt[3]{x^3} = x

πŸ’‘Examples

Problem 1:

Simplify the expression: 57Γ—5356\frac{5^7 \times 5^3}{5^6}

Solution:

Step 1: Use the Product Rule on the numerator: 57Γ—53=57+3=5105^7 \times 5^3 = 5^{7+3} = 5^{10}. \ Step 2: Rewrite the expression as 51056\frac{5^{10}}{5^6}. \ Step 3: Use the Quotient Rule: 510βˆ’6=545^{10-6} = 5^4. \ Step 4: Calculate the final value if required: 5Γ—5Γ—5Γ—5=6255 \times 5 \times 5 \times 5 = 625.

Explanation:

We first combined the powers in the numerator by adding their indices, then simplified the division by subtracting the index of the denominator from the index of the numerator.

Problem 2:

Evaluate the following: 3Γ—64+233 \times \sqrt{64} + 2^3

Solution:

Step 1: Calculate the square root: 64=8\sqrt{64} = 8 (since 8Γ—8=648 \times 8 = 64). \ Step 2: Calculate the power: 23=2Γ—2Γ—2=82^3 = 2 \times 2 \times 2 = 8. \ Step 3: Substitute the values back into the expression: 3Γ—8+83 \times 8 + 8. \ Step 4: Follow the order of operations (multiplication first): 24+8=3224 + 8 = 32.

Explanation:

This problem combines square roots, exponents, and the order of operations (BODMAS/BIDMAS). We solve the root and the power first before multiplying and adding.