1.5-Laws of Exponents
1.5-Laws of Exponents Important Formulae
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Grade 9 → Math → Number Systems → 1.5-Laws of Exponents
- Understand laws of exponents.
Exponents are a way to express repeated multiplication of a number by itself. The laws of exponents provide rules for simplifying expressions involving powers, making calculations easier. Here are the key laws of exponents:
1. Product of Powers:
When multiplying two expressions with the same base, you add the exponents:
$$ a^m \times a^n = a^{m+n} $$For example, if $a = 2$, $m = 3$, and $n = 2$:
$$ 2^3 \times 2^2 = 2^{3+2} = 2^5 = 32 $$2. Quotient of Powers:
When dividing two expressions with the same base, you subtract the exponent of the denominator from the exponent of the numerator:
$$ \frac{a^m}{a^n} = a^{m-n} \quad (a \neq 0) $$For example, if $a = 5$, $m = 4$, and $n = 2$:
$$ \frac{5^4}{5^2} = 5^{4-2} = 5^2 = 25 $$3. Power of a Power:
When raising a power to another power, you multiply the exponents:
$$ (a^m)^n = a^{m \cdot n} $$For example, if $a = 3$, $m = 2$, and $n = 4$:
$$ (3^2)^4 = 3^{2 \cdot 4} = 3^8 = 6561 $$4. Power of a Product:
When taking a power of a product, you distribute the exponent to each factor in the product:
$$ (a \times b)^n = a^n \times b^n $$For example, if $a = 2$ and $b = 3$, with $n = 3$:
$$ (2 \times 3)^3 = 2^3 \times 3^3 = 8 \times 27 = 216 $$5. Power of a Quotient:
When taking a power of a quotient, you apply the exponent to both the numerator and the denominator:
$$ \left(\frac{a}{b}\right)^n = \frac{a^n}{b^n} \quad (b \neq 0) $$For example, if $a = 4$, $b = 2$, and $n = 2$:
$$ \left(\frac{4}{2}\right)^2 = \frac{4^2}{2^2} = \frac{16}{4} = 4 $$6. Zero Exponent:
Any non-zero base raised to the power of zero is equal to one:
$$ a^0 = 1 \quad (a \neq 0) $$For example:
$$ 7^0 = 1 $$7. Negative Exponent:
A negative exponent represents the reciprocal of the base raised to the opposite positive exponent:
$$ a^{-n} = \frac{1}{a^n} \quad (a \neq 0) $$For example:
$$ 2^{-3} = \frac{1}{2^3} = \frac{1}{8} $$Understanding these laws of exponents is crucial for simplifying expressions and solving equations in algebra and other areas of mathematics. They provide a systematic way to handle calculations involving powers and roots.
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