Direct or Inverse

When x = 2, y = 12. Find the value of y when x = 4 if
y varies inversely as x.

Answer explanation

y = k/x
We use the given (2,12) to find k
k = xy
k = 2(12)
k = 24.
So y = 24/x
then y = 24/4
y = 6.

y = 24 when x = 5. Find the value of x when y = 2 if
y varies directly as x.

• 24/5

• 48/5

• 5/12

• 10/12

Answer explanation

y =kx
We use the given (5,24) to find k.
k = y/x
k = 24/5 ---- keep the fraction for accuracy purpose
y = (24/5)x
Find x when y =2.
x = 5y/24
x = 5(2)/24
x = 5/12

y = 24 when x = 5. Find the value of x when y = 2 if
y varies inversely as x³.

• 3000

• 1500

x=2, y=30
x=4, y =15
x=6, y =10
x=12, y =5
These values are from a function where y varies ____ as x.

Answer explanation

Notice that xy is always 60.
So the proportionality constant k = 60
k = xy then y = k/x.
Thus, y is varies inversely as x.

Tags

CCSS.HSF-LE.A.1B

x=2, y=30
x=4, y =15
x=6, y =10
x=12, y =5
Find the proportionality constant of the function for these values.

Answer explanation

Notice that xy is always 60.
So the proportionality constant k = 60
k = xy then y = k/x.
In this case, y is varies inversely as x.

Tags

CCSS.HSF-LE.A.1B

Is the table Direct or Inverse Variation?

• Direct

• Inverse

If x and y vary directly find the missing value.

(4, y) (-6, 15)

• 22.5

• 10

• -22.5

• -10

If x and y vary inversely, find the missing value.

(4, 21) (x, 12)

• 7

• -7

• 2.29

• -2.29

Is the Table Direct or Inverse

• Direct

• Inverse

In the table what is the constant?

K =

Write the number only

Tags

CCSS.HSF-LE.A.1B