Mastering Exponential and Logarithmic Functions Guide
Enhance your understanding of exponential and logarithmic functions with this comprehensive guide by Dr. Carol A. Marinas. Learn conversions, properties, equations, and more in an easy-to-follow format. Dive into exponential and logarithmic relationships, logarithmic abbreviations, properties, examples, and equations. Conquer exponential and logarithmic problem-solving with step-by-step explanations and shortcuts. This guide simplifies complex concepts and helps you excel in math.
Mastering Exponential and Logarithmic Functions Guide
E N D
Presentation Transcript
Exponential & Logarithmic Functions Dr. Carol A. Marinas
Table of Contents • Exponential Functions • Logarithmic Functions • Converting between Exponents and Logarithms • Properties of Logarithms • Exponential and Logarithmic Equations
General Form of Exponential Function y = b x where b > 1 • Domain: All reals • Range: y > 0 • x-intercept: None • y-intercept: (0, 1)
General Form of Exponential Functiony = b (x + c) + dwhere b > 1 • c moves graph left or right (opposite way) • d move graph up or down (expected way) • So y=3(x+2) + 3 moves the graph 2 units to the left and 3 units up • (0, 1) to (– 2, 4)
Relationships of Exponential (y = bx) & Logarithmic (y = logbx) Functions • y = logbx is the inverse of y = bx • Domain: x > 0 • Range: All Reals • x-intercept: (1, 0) • y-intercept: None • y = bx • Domain: All Reals • Range: y > 0 • x-intercept: None • y-intercept: (0, 1)
Relationships of Exponential (y = bx) & Logarithmic (y = logbx) Functions
BASEEXPONENT = POWER 42 = 16 4 is the base. 2 is the exponent. 16 is the power. As a logarithm, logBASEPOWER=EXPONENT log 4 16 = 2 Converting between Exponents & Logarithms
Logarithmic Abbreviations • log10 x = log x (Common log) • loge x = ln x (Natural log) • e = 2.71828...
logb(MN)= logbM + logbN Ex: log4(15)= log45 + log43 logb(M/N)= logbM – logbN Ex: log3(50/2)= log350 – log32 logbMr = r logbM Ex: log7 103 = 3 log7 10 logb(1/M) = logbM-1= –1 logbM = – logbM log11 (1/8) = log11 8-1 = – 1 log11 8 = – log11 8 Properties of Logarithms
Properties of Logarithms (Shortcuts) • logb1 = 0 (because b0 = 1) • logbb = 1 (because b1 = b) • logbbr = r (because br = br) • blog b M = M (because logbM= logbM)
Examples of Logarithms • Simplify log 7 + log 4 – log 2 = log 7*4 = log 14 2 • Simplify ln e2= 2 ln e = 2 logee = 2 * 1 = 2 • Simplify e 4 ln 3 - 3 ln 4= e ln 34 - ln 43 = e ln 81/64 = e loge81/64 = 81/64
logam logbm = -------- logab log712 = log 12 log 7 OR Change-of-Base Formula • log712= ln 12 • ln 7
Exponential & Logarithmic Equations • If logb m = logb n, then m = n. If log6 2x = log6(x + 3), then 2x = x + 3 and x = 3. • If bm = bn, then m = n. If 51-x = 5-2x, then 1 – x = – 2x and x = – 1.
If your variable is in the exponent….. • Isolate the base-exponent term. • Write as a log. Solve for the variable. • Example: 4x+3 = 7 • log4 7 = x + 3 and – 3 + log4 7 = x OR with change of bases: x = – 3 + log 7 log 4 • Another method is to take the LOG of both sides.
Logarithmic Equations • Isolate to a single log term. • Convert to an exponent. • Solve equation. • Example: log x + log (x – 15) = 2 • log x(x – 15) = 2 so 102 = x (x – 15) and 100 = x2 – 15x and 0 = x2 – 15x – 100 So 0 = (x – 20) (x + 5) so x = 20 or – 5