Question

Write an equation with a slope of -1/2 in each form. point-slope form slope-intercept form.

Answer 1

For the case of a line through

(

2

,

7

)

and

(

1

,

−

4

)

we have

slope

m

=

Δ

y

Δ

x

=

−

4

−

7

1

−

2

=

−

11

−

1

=

11

Using the point

(

2

,

7

)

we can write the equation of the line in point slope form as:

y

−

7

=

m

(

x

−

2

)

where the slope

m

=

11

.

That is:

y

−

7

=

11

(

x

−

2

)

To get point intercept form, first expand the right hand side so...

y

−

7

=

11

x

−

(

11

⋅

2

)

=

11

x

−

22

Then add

7

to both sides to get:

y

=

11

x

−

15

=

11

x

+

(

−

15

)

This is point intercept (

y

=

m

x

+

c

) form with slope

m

=

11

and intercept

c

=

−

15

.