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Example 2:
Identifying direct variation from an Equation
You can write equation to solve a direct variation problem.
Y=12x
Y varies directly with X,
The constant of variation is 2/3
Y= 2x +3
You can't write the equation in the form of Y=k x
Y does not vary directly with x
Example: 3
Using proportions,
Using proportions to solve direct variation problems can save a lot of time when
the problem does not ask for the constant variation.
So suppose y varies directly with x, and x =2 when y is 6. Find x when y=12
Y1/X1=Y2/X2(write a proportion)
6/2= 12/X2(substitute)
6(X2)= 2(12) (Write the cross products)
X2= 24/6 (Solve for X2)
X2 = (Simplify)