3.4-7 Flashcards

(47 cards)

1
Q

lne=1 as exp

A

e^1=e

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2
Q

is it possibe for a log function to have nagative outputs in the form y=logbx

A

yes if b is whole and a is fractions

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3
Q

is it possibe for a log function to have c<b<a in the form a=logbc

A

yes when 3=log1/2(1/8)

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4
Q

log b definition

A

b>0

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5
Q

parent ln

A

y=lnx

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6
Q

1/x

A

horzionatal stretch

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7
Q

why all graphs of logs pass through (1,0) and (b,1)

A

b^0=1 and b^1=b)

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8
Q

log func graphs must pass thru

A

(1,0) and (b,1)

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9
Q

-log

A

reflect over x

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10
Q

log(-x)

A

reflect over y

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11
Q

writing log equation

A

find shift, do opposite direction to find base of va

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12
Q

va shows

A

left vs right shift

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13
Q

passing thru point

A

just check

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14
Q

how to find inverse of a log from a graph

A

reflect the original graph across the line (y=x). Another method is to pick a few points on the original log graph, switch the x and y coordinates for each point, and plot these new points to sketch the inverse graph. The inverse of a logarithmic function is always an exponential function.

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15
Q

expanding logs with division

A

al in denominator will be negative

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16
Q

relationship between exponent and log properties

A

both involve addition for products with like bases

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17
Q

a/b=e^c

A

lna/b=c

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18
Q

output of a log func

A

tells you what exponent you must raise the base to in order to arrive at the input

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19
Q

log from

20
Q

exp form

21
Q

common log

A

if no subscript is given, assume b=10

22
Q

natural log

A

if base is e, logex=lnx

23
Q

domain

A

(0,inf) since powers of b are always positive

24
Q

range

A

(-inf, inf) since exponents can be negative or positve

25
relationship between log and inverse exp
domains and range are just inversed
26
transformations affect
x intercept, asymptoes, domain
27
parent log functions
y=logbx for any base b>0 b not equal 1
28
2 key points
(1,0) x intercept (b,1) identity
29
vertical asymptoe
x=0
30
b^x and logbx
inverse
31
expanded form logbx+logby
logbxy
32
expanded logic-logby
log(x/y)
33
alogb^x
logbx^a
34
estimating x^?
choose values in between and guess
35
log negatives
none unless shift
36
strategies for solving exp and logs
apply log properties, ise inverse operationsm, reweire in alternate form to isolate variable
37
one to one property
if b^x=b^y, x=y and if logbx=logby then x=y so same output means same inpout
38
uusing calculator
find intersectoion of two graphs
39
x^1/2
root x
40
use ln as
log with e to undo exponential increase
41
use answer in exponential form
then set equal to other exponential
42
look at x interept using calculator then
insert both sides of equation
43
order for transformations
h shift, y stretch/reflect, h stretch/reflect, v shift
44
reflect over x
x,y to x,-yl
45
log domain and range
range always inf, domain is ^(x+this value) to inf
46
exp domain and range
domain always inf, range is + his value to inf
47
log transfoamations
change log to f(x)