Cambridge Additional Mathematics

188 Straight line graphs (Chapter 7)

Example 12 Self Tutor

Findyin terms ofx:

ab

a The graph ofyagainstx^3 is linear.

The gradient is

11 ¡ 5

3 ¡ 0

=2, and

they-intercept is 5.

) the equation is y=2x^3 +5.

b The graph ofyagainst

p

xis linear.

) the equation is

y¡2=^34 (

p

x¡4)

) y¡2=^34

p

x¡ 3

) y=^34

p

x¡ 1 , x> 0

Example 13 Self Tutor

a Findyin terms ofx.

b Findywhen x=4.

a

) the equation is

y

x

¡4=

1

2

(x¡2)

)

y

x

¡4=

1

2

x¡ 1

)

y

x

=

1

2

x+3

) y=^12 x^2 +3x

b When x=4, y=^12 (4)^2 + 3(4)

=20

y

O x 3

5

(3 11),

Bv

O x

(2 4),

(8 7),

y

O ~`x

(4 2),

(8 5),

The graph of

y

x

againstxis linear.

The gradient is

7 ¡ 4

8 ¡ 2

=

1

2

.

The gradient is

5 ¡ 2

8 ¡ 4

=

3

4

.

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Additional Mathematics
Y:\HAESE\CAM4037\CamAdd_07\188CamAdd_07.cdr Monday, 6 January 2014 9:18:59 AM BRIAN