Laws of Indices in Algebra: Multiplying and Dividing Monomials and Managing Exponents
In this lesson, we advance to multiplication and division of algebraic terms, operations governed by the rigorous laws of exponents. Unlike addition and subtraction, multiplication and division DO NOT require like terms. In 'monomial multiplication', we multiply the numerical coefficients first (adhering strictly to sign rules: positive × positive = positive, negative × negative = positive, opposite signs = negative), and then multiply variable factors by applying the 'Product Law of Indices': when multiplying powers with identical bases, we add the exponents: (a^m × a^n = a^(m+n)). In 'monomial division', we divide the numerical coefficients and apply the 'Quotient Law of Indices': when dividing powers with identical bases, we subtract the exponents: (a^m ÷ a^n = a^(m-n)) for non-zero base a. Furthermore, we emphasize the 'Zero Exponent Rule': any non-zero variable raised to the power of zero equals 1: (x⁰ = 1 for x ≠ 0). These exponential laws form the backbone of analytical calculation across science and engineering.
1. Monomial Multiplication & Adding Exponents
Rules for multiplying terms:
- Coefficients: Multiply numbers and signs first: (3) × (-4) = -12.
- Add Exponents: For identical bases: x^m × x^n = x^(m+n).
- Example: (2x²y) × (5x³y⁴) = (2 × 5)(x^(2+3))(y^(1+4)) = 10x⁵y⁵.
- Different Letters: Simply written beside each other: (3x) × (2y) = 6xy.
2. Monomial Division & Subtracting Exponents
Rules for dividing terms:
- Coefficients: Divide numerator by denominator: 15 ÷ -3 = -5.
- Subtract Exponents: For identical bases: x^m ÷ x^n = x^(m-n).
- Example: (12x⁵y²) ÷ (4x²y) = (12 ÷ 4)(x^(5-2))(y^(2-1)) = 3x³y.
- Zero Exponent: x ÷ x = x^(1-1) = x⁰ = 1 (where x ≠ 0).
Step-by-Step Computational Workshop:
Multiply coefficients: (-3) × (4) = -12.
Add powers of a: 2 + 1 = 3 → a³.
Add powers of b: 3 + 2 = 5 → b⁵.
Final Product = -12a³b⁵.
Divide coefficients: 20 ÷ (-5) = -4.
Subtract powers of x: 4 - 2 = 2 → x².
Subtract powers of y: 3 - 3 = 0 → y⁰ = 1.
z remains in numerator.
Final Quotient = -4x²z.
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