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12345More exponential functions

Solutions to the exercises

Exercise 1
a

f ( x ) = 1 4 2 x - 3 : multiplication of a ( x ) = 2 x with 1/4 with respect to the x -axis and a translation of -3 along the y -axis
g ( x ) = 1 2 0.5 x - 1 : multiplication of b ( x ) = ( 1 2 ) x with 1/2 with respect to the x -axis and a translation of -1 along the y -axis

b

2 x - 2 = 2 -3 gives x = -1

c

( 1 3 ) x - 3 = 5 8 gives x 3.68 . Solution: x < 3.68

d

g ( 4 ) = 1 . Graph: if x 4 , then g ( x ) 1 .

e

Study the graphs: -3 < p -1

f

A = ( -1 , -2 7 8 ) and B = ( -1 , 63 ) . So the length of A B is 63 -2 7 8 = 65 7 8 .

g

C = ( 5 , 5 ) en B ( 2,415 ; 5 ) . Dus is C D 5 2,415 = 2 ,585 .

Exercise 2
a

x 1.43

b

x 1.43

c

5 x = 5 3 gives x 0.32

d

x 0.32

e

x -0.63

f

x -0.63

g

( 1 3 ) x = 2 gives x -0.63

h

x > -0.63

Exercise 3
a

2 x = 2 1 1 2 gives x = 1 1 2

b

2 2 x = 2 3 ( x + 2 ) gives x = -6

c

3 4 x = 3 1 2 gives x = 1 8

d

2 2 x - 1 = 2 5 gives x = 3

e

2 1 2 x + 1 = 2 2 1 2 gives x = 3

f

2 2 x = 2 0 gives x = 0

g

2 3 x 2 = 2 4 x gives x = 0 x = 4 3

h

2 - x = 2 3 gives x = -3

i

2 x + 5 = 2 2 gives x = -3

j

2 5 ( 3 x - 2 ) = 2 -2 gives x = 8 15

Exercise 4
a

x = 3

b

p = 4

c

t = 2

d

x < 4

e

x 1

f

x -4

Exercise 5
a

x > 2

b

x < 2

c

x < 0.17

d

x > 1.5

e

x > -49

f

x 3

g

x < 2.5

Exercise 6
a

540 0.95 t is decreasing, so 540 - 540 0.95 t is increasing.

b

A = 540

c

The medication enters the blood slower and slower.

d

Solving 405 = 540 - 540 0.95 t gives t 27.03 , so just after 27 minutes.

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