Cambridge Additional Mathematics

190 Straight line graphs (Chapter 7)

Example 14 Self Tutor

Writeyin terms ofx, giving your answer in the form

y=a£ 10 bx, where a,b 2 Q.

The graph of lgy againstxis linear.

The gradient is^4 ¡^3

6 ¡ 3

=^13.

) the equation is lgy¡3=^13 (x¡3)

lgy¡3=^13 x¡ 1

) lgy=^13 x+2

) y=10

1

3 x+2 fif lgp=q then p=10qg

) y=10

1

3 x£ 102

) y= 100£ 10

1

3 x

3aFind lgy in terms ofx.

b Writeyin terms ofx, giving your answer in the form

y=a£ 10 bx, where a,b 2 Q.

4 Writeyin terms ofx, giving your answer in the form

y=a£ 10 bx, where a,b 2 Q.

5 Writeyin terms ofx, giving your answer in the form y=a£bx, where a,b 2 Q.

abc

In , we saw that a

linear relationship between

and indicates an

exponential relationship

between and.

Chapter 5

lgyx

yx

lgy

O x

(1 1),

(3 5),

lgy

O x

(3 3),

(6 4),

lgy

O x

(-1 4 5),.

2

lgy

x

(8 4),

(2 -2),

O

lgy

O x

(1 3),

4

lgy

O x

lg 5

(1,lg20)

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100 100 4037 Cambridge
Additional Mathematics
Y:\HAESE\CAM4037\CamAdd_07\190CamAdd_07.cdr Thursday, 3 April 2014 5:48:35 PM BRIAN