CHAPTER 5-5 DIRECT VARIATIONS.
Direct Variartion- y=kx where k doesn't equal 0, when two variable quantities have a constant unchanged ratio,
The constant of variation-k is the coefficient of x.
ex. Is each equation a direct variation? Check by solving for y.
5x+2y=9
2y=9-5x
y=9/2- 5/2x.
NO, it's not a direct variation because the equation cannot be written in the form of y=kx.
ex.
For the table, use the ratio y/x to tell wheter y varies directly with x.
X Y y/x
No because y doesn't vary directly with x, so it is not a direct variation.
ex. write an equation of the direct variation that includes the given point.
(35,7)
y=kx - Begin with the function form of a direct variation.
7=k(35) - Plug your x and y into the equation.
7/35=k - Divide each side by 35 to solve for the k.
y=7/35 - Write an equation.Substitue 7/35 for k in y=kx
<------------EVEN HE CAN DO IT!!!!!!!!!!!!!!!
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