Question

Graph line of the equation y=−2x−2

Answer 1

Explanation:

The minimum number of points needed to draw a strait line graph is 2. However, 3 is better as one of them forms a check. They should all line up. If not then something is wrong.

Lets determine 2 points

The line will 'cross' the y axis at

x

=

0

and cross the x axis at

y

=

0

So we can determine these points (intercepts) by substitution.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For y-intercept set

x

=

0

giving:

y

=

2

x

.

.

+

2

y

=

(

2

×

0

)

+

2

→

y

=

2

So y-intercept is at the point

(

x

,

y

)

=

(

0

,

2

)

For x-intercept set

y

=

0

giving:

0

=

2

x

+

2

Subtract

2

from both sides

0

−

2

=

2

x

+

2

−

2

−

2

=

2

x

+

0

Divide both sides by

2

−

2

2

=

2

2

×

x

But

−

2

2

=

−

1

and

2

2

=

+

1

−

1

=

x

So the y-intercept is at the point

(

x

,

y

)

=

(

−

1

,

0

)