Direct variation

Direct Variation

Lesson 1

Problem: "x varies directly with y".

If x = 12 when y = 24, find y when x = 10

Solution The formula for direct variation is x = ky, where k is the constant of variation.

Step 1:

Solution x varies directly with y"

Step 2:

Solution k = x/y = 12/24 = 1/2

Step 3:

Solution Other values of x and y will have same constant of variation k = 1/2 = 10/y

Step 4:

Solution Solve for y by cross multiply: y = 20

Step 5:

Solution Answer: 20

Step 6:

Complete

Try two practice problems:

A. "m varies directly with n".

If m = 5 when n = 10, find n when m = 4.

B. Write equation which represents: y varies directly with x,

if x = 12.