Exponents are a fundamental building block of algebra. This guide breaks down the core concepts and rules found in the Exponents curriculum.
1. Understanding Exponential Form
Exponential form is a shorthand way to write repeated multiplication of the same number3.
- $a^{2}$: Read as ‘$a$ squared’ or ‘$a$ power 2’.
- $a^{3}$: Read as ‘$a$ cubed’ or ‘$a$ power 3’.
- $a^{n}$: Represents $a$ multiplied by itself $n$ times.
- Prime Factorization: You can express large numbers like 432 as a product of prime factors (e.g., $432 = 2^{4} \times 3^{3}$).
2. Key Laws of Exponents
To simplify mathematical expressions, use these essential formulas8888:
| Rule | Formula | Example |
| Product Law | $a^{m} \times a^{n} = a^{m+n}$ | $2^{5} \times 2^{10} = 2^{15}$ |
| Quotient Law | $\frac{a^{m}}{a^{n}} = a^{m-n}$ | $\frac{5^{7}}{5^{2}} = 5^{5}$ |
| Power of a Power | $(a^{m})^{n} = a^{mn}$ | $(7^{5})^{2} = 7^{10}$ |
| Power of a Product | $(ab)^{n} = a^{n}b^{n}$ | $(2x)^{3} = 8x^{3}$ |
| Power of a Quotient | $(\frac{a}{b})^{n} = \frac{a^{n}}{b^{n}}$ | $(\frac{2}{3})^{2} = \frac{4}{9}$ |
| Zero Exponent | $a^{0} = 1$ (where $a \ne 0$) | $100^{0} = 1$ |
Pro Tip: Remember that $0^{0}$ is always undefined.
3. Negative Exponents and Reciprocals
A negative exponent indicates the reciprocal of the base.
- Basic Rule: $a^{-n} = \frac{1}{a^{n}}$.
- Fractional Rule: $(\frac{a}{b})^{-n} = (\frac{b}{a})^{n}$.
- Example: $(\frac{3}{4})^{-2} = (\frac{4}{3})^{2} = \frac{16}{9}$.
4. Rules for Negative Bases
When dealing with negative bases like $(-1)$ or $(-a)$, the result depends on whether the exponent is even or odd:
- Even Exponents: Result is positive (e.g., $(-1)^{100} = 1$ or $(-3)^{4} = 81$).
- Odd Exponents: Result is negative (e.g., $(-1)^{201} = -1$ or $(-5)^{3} = -125$).
5. Solving for $x$ in Exponential Equations
If $a^{m} = a^{n}$ and the base $a$ is not $-1, 0,$ or $1$, then the exponents must be equal ($m=n$).
- Example: If $4^{2x+7} = 64$30:
- Rewrite 64 as $4^{3}$31.
- Set exponents equal: $2x + 7 = 3$32.
- Solve: $2x = -4$, so $x = -2$33.
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