1. TODAY IN PRECALCULUS Go over homework Notes: (no handout, need a calculator) Condensing Log Expressions –Change of Base formula Homework

2. Condensing Log Expressions Example: condense: log 5 x - log 5 y Example: Condense: 2log 2 x+log 2 y Example: Condense: 3lnx + 4 ln(y+4)

3. Example: condense: 4[lnz + ln(z+5)] – 2ln(z-5)

4. condense: log 3 x + log 3 7 7log 8 (x+4) 2[3log 4 x + log 4 (x+1)-log 4 (x-1)] log 10 x + 2log 10 y - 3log 10 z lnx – 4[ln(x+2) + ln(x-2)] Practice

5. Change of Base Formula Allows us to rewrite logs in terms of base 10 or e so we can calculate the value of the log.

6. Example Find the value log 4 28 Rewrite log 8 x as a ratio of both common and natural logs

7. Homework Page 317: 13-22all, 23-35odd

8. log 3 x + log 3 7 = log 3 7x 7log 8 (x+4) = log 8 (x+4) 7 2[3log 4 x + log 4 (x+1)-log 4 (x-1)] = 2[log 4 x 3 + log 4 (x+1)-log 4 (x-1)]

9. log 10 x + 2log 10 y - 3log 10 z =log 10 x + log 10 y 2 - log 10 z 3 = lnx – 4[ln(x+2) + ln(x-2)] = lnx – 4[ln(x+2)(x-2)] = lnx – ln[(x+2)(x-2)] 4