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Uncover the secrets of the number "e" and natural logarithms, learn to solve equations, and understand their significance in mathematics.
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6.7 – Base “e” and Natural Logarithms Objective – TSW solve equations that contain “e” and natural logarithms.
What is this “e” business about ? “e” is a number like pi. - It is a non repeating, never ending decimal. - An irrational number. - e ≈ 2.71828… - e is the base of the natural log (ln)…just like 10 is the base of log.
On your calculators…Let’s Practice Using “e” • e9 2. e3.4 3. 3e0.05 4. e1/4
Why do we use “e” • Because in the natural log (ln) the base is e. ALL PROPERTIES of logarithms apply to natural logarithms. • Anytime you see ln…you can write loge • For example: ln 3 means loge 3
Let’s look at this “ln” business. • ln 99,999 2. ln 0.994 3. ln ½ 4. ln (-2) 5. ln (15)
Examples…Write each exponential equation in logarithmic form or each logarithmic equation in exponential form. • ex = 8 2. e5 = x 3. e7 = x 4. ln x = 0.7741 5. ln 10 = x 6. ln x = 2.1438
Write each expression as a single logarithm. • 3 ln 10 – ln 8 8. ln 40 + 2ln ½ + ln x 9. 6ln 8 – 2ln 4 10. 2ln 5 + 4ln 2 + ln 5y
To Solve natural log equations: • Identify whether the equation is in log form or exponential form. • Get the “log/ln” portion by itself OR get the “exponential” portion by itself. • Rewrite into either log or exponential form. • Solve. • Check your answer. ***REMEMBER ln means loge***
Homework… Pg. 529 #’s 1-14(all), 34, 36, 38