2. Direct Variation
When we talk about a direct
variation, we are talking about
a relationship where as
x increases,
y increases
or decreases at a CONSTANT
RATE.
5. Direct Variation
If y varies directly as x and y = 10
find x when y =15.
y = 10, x = 2.4
make these y1 and x1
y = 15, and x = ?
make these y2 and x2
6. Direct Variation
if y varies directly as x and y = 10
as x = 2.4, find x when y =15
10
2.4
=
15
x
12. Inverse Variation
Inverse is very similar to
direct, but in an inverse
relationship as one value goes
up, the other goes down.
There is not necessarily a
constant rate.
13. Inverse Variation
With Direct variation we
Divide our x’s and y’s.
In Inverse variation we will
Multiply them.
x1y1 = x2y2
14. Inverse Variation
If y varies inversely with x and
y = 12 when x = 2, find y when x = 8.
x1y1 = x2y2
2(12) = 8y
24 = 8y
y = 3
15. Inverse Variation
If y varies inversely as x and x = 18
when y = 6, find y when x = 8.
18(6) = 8y
108 = 8y
y = 13.5