IXL - Solve variation equations (Algebra 2 practice)

or

A direct variation includes the points

(

3

,

72

)

and

(

–

2

,

n

)

.

Find

n.

Write and solve a direct variation equation to find the answer.

n

=

ref_doc_title.

or

Learn with an example

question

An
inverse
variation
includes
the
points
(10, 4)
and
(5, n)
.
Find
n .

Write and solve an inverse variation equation to find the answer.

n =

key idea

Inverse variation
can
be
represented
by
the
equation
y
=
k
x
or
xy = k
.

The variable k is known as the constant of variation, and it cannot equal zero.

solution

First
find
the
constant
of
variation.
Plug
x = 10
and
y = 4
into
the
inverse
variation
equation
and
then
solve
for
k .

xy

=

k

(10)(4)

=

k

40

=

k

Now
use
k
=
40
to
write
the
inverse
variation
equation.

y

=

k

x

y

=

40

x

The
inverse
variation
equation
is
y
=
40
x
.
This
can
also
be
written
as
xy = 40
.

Finally,
use
the
inverse
variation
equation
to
find
n
when
x = 5
.
It
is
easiest
to
use
the
first
equation,
y
=
40
x
.

y

=

40

x

n

=

40

5

n

=

8

So,
n = 8
.

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Work it out

Not feeling ready yet? These can help:

Y.1Write and solve direct variation equations

Y.2Write and solve inverse variation equations

Y.6Write joint and combined variation equations II