110 likes | 234 Vues
This comprehensive overview covers crucial properties of logarithms, including the Product, Quotient, and Power properties. Practical examples demonstrate how to expand and condense logarithmic expressions effectively. By utilizing approximate logarithmic values for log 5 and log 7, learners can practice calculations involving logarithmic expressions and hone their skills in applying these properties in various contexts. Includes assignments to reinforce learning. Perfect for students seeking to master logarithm concepts!
E N D
8.5Properties of logarithms p. 493
Properties of Logarithms • Let b, u, and v be positive numbers such that b≠1. • Product property: • logbuv = logbu + logbv • Quotient property: • logbu/v = logbu– logbv • Power property: • logbun = n logbu
Use log53≈.683 and log57≈1.209 • Approximate: • log53/7 = • log53 – log57 ≈ • .683 – 1.209 = • -.526 • log521 = • log5(3·7)= • log53 + log57≈ • .683 + 1.209 = • 1.892
Use log53≈.683 and log57≈1.209 • Approximate: • log549 = • log572 = • 2 log57 ≈ • 2(1.209)= • 2.418
Expanding Logarithms • You can use the properties to expand logarithms. • log2 = • log27x3 - log2y = • log27 + log2x3 – log2y = • log27 + 3·log2x – log2y
Your turn! • Expand: • log 5mn= • log 5 + logm + logn • Expand: • log58x3 = • log58 + 3·log5x
Condensing Logarithms • log 6 + 2 log2 – log 3 = • log 6 + log 22 – log 3 = • log (6·22) – log 3 = • log = • log 8
Your turn again! • Condense: • log57 + 3·log5t = • log57t3 • Condense: • 3log2x – (log24 + log2y)= • log2
Change of base formula: • u, b, and c are positive numbers with b≠1 and c≠1. Then: • logcu = • logcu = (base 10) • logcu = (base e)
Examples: • Use the change of base to evaluate: • log37 = • (base 10) • log 7 ≈ • log 3 • 1.771 • (base e) • ln 7≈ • ln 3 • 1.771