Rational Functions: Direct and Inverse Variation

think icon Think & Click: Predicting Values

Now, you try. Complete the Think & Click activity by looking at each problem below, thinking about it, and then clicking on the question to reveal the solution.

If y varies directly as x, and y = 16 as x = 4, what will be the value of y if x = 3?
 

y = kx
16 = k(4)
k = 4

y = 4x
y = 4(3) = 12

When x = 3, y = 12.

 

If y varies inversely as x, and y = 8 as x = 4, what will be the value of y if x = 2?
 

y equals k divided by x, 8 equals k divided by 4, k equals 32

y equals 32 divided by x, y equals 32 divided by 2, y equals 16

When x = 2, y = 16.