Summary.....The Big Picture : Log's and Exponential
Functions
Def'n.:
ln(x) = ò1x
1/t dt
[ x>0] |
Def'n.:
exp (x) = y Û
ln(y) = x
exp(1) º e [so
ln(e) = 1].
exp(x) º ex |
Def'n.:
For b >0,
bx º
e xln(b).
Note: ln(bx) = x ln(b) |
Def'n.:
For b >0,
log b (x) = y Ûx=
by |
ln(1) = 0
ln(x) > 0 for x >1
ln(x) < 0 for 0< x <1 |
exp(0) = e0=1
ex> 1 for x > 0
0< ex < 1 for x < 0 |
b0 = 1
For b > 1:
b x > 1 for x >
0
0< bx < 1 for x < 0
For 0< b < 1:
b x > 1 for x <
0
0< bx < 1 for x > 0 |
log b (1) = 0
For b > 1:
log b (x)>0 for x >1
log b (x)<0 for 0< x <1
For 0< b < 1:
log b (x)<0 for x >1
log b (x)>0 for 0< x <1 |
ln(A*B) = ln(A) + ln(B) |
eAeB =eA+B |
bAbB = bA+B |
log b (A*B) = log b (A) + log b
(B) |
ln(A/B) = ln(A) - ln(B) |
eA / eB = eA-B |
bA /bB = bA-B |
log b (A/B) = log b (A ) - log
b (B) |
ln(Ap/q) =p/q ln(A) |
(ex) p/q = e(p/q)*x |
(bx) p/q = b(p/q)*x |
log b (Ap/q )= p/q log b
(A) |
ln'(x) = D ln(x) = 1/x
[So ln is continuous and increasing for x >0] |
exp'(x) = D(ex) = ex |
D(bx) = ln(b) bx |
log b'(x) = D log b
(x) = 1/( x ln(b)) |
ò
1/u du = ln|u| + C |
òeu
du = eu + C |
ò bu
du = bu / ln(b)
+ C |
Not relevant! |
As x ® ¥, ln
(x) ® ¥. |
As x ® ¥, ex®
¥. |
b >0: As x ® ¥, bx®
¥.
b <0:As x ® ¥ ,
bx® 0 |
For b > 1:As x ® ¥, log
b (x) ®
¥.
For 0< b < 1:As x ®
¥, log b (x)®
- ¥. |
As x ® 0+ , ln(x)
® - ¥ |
As x ® - ¥ , ex®
0 |
b>0: As x ® - ¥ ,
bx® 0
b<
0:As x ® - ¥, bx®
¥. |
For b > 1:As x ® 0+,
ln (x) ®
- ¥
For 0< b < 1:As x ®
0+, ln (x)
® ¥ |
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