IXL | Find the equation of a graph

Look at this graph.

200

400

600

800

1,000

200

400

600

800

1,000

Select the equation for the relationship shown in the graph.

y = x + 100

y = x − 700

y = x + 700

y = x + 200

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Learn with an example

question

Look at this graph.

100

Select the equation for the relationship shown in the graph.

y = ^–8x

y = 8x

^–1

key idea

The equation of a line that passes through the origin is y = mx.

rise

run

solution

The graph is a straight line that passes through the origin, so the equation is y = mx.

Find the slope m. Pick two points on the line, such as (0, 0) and (10, 80).

100

To get from (0, 0) to (10, 80), you move up 80 and right 10. So, the rise is 80 and the run is 10.

Now plug this into the slope formula:

slope

rise

run

80 − 0

10 − 0

The slope m is

Now plug

m =

into the equation y = mx.

The equation for the line in the graph is

y = 8x

Looking for more? Try these:

Lesson: Slope-intercept form

$Confetti$

Excellent!

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Teacher tools

Work it out

Not feeling ready yet? These can help:

X.4Find the constant of proportionality from a graph

AA.6Write a linear equation from a slope and y-intercept

Lesson: Slope-intercept form

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