Variations and formulas (Chapter 6)

*Relationships- in mathematics a relationship is a connection between two variables; changing the value of one of the variables changes the value of the other.
*Variable- letter or symbol used o represent quantity that can change.
*Variation- A relationship between two variables which can be expressed as a formula, a table of values, or as a graph.
*Direct variation- the relationship between two variables x and y with the form y=kx where k is constant. A direct variation may be represented by a straight line graph which passes through the origin (0,0)
*Constant of variation- the value of k in the direct variation formula y=kx. K is equal to the slope of the line when thre variation is graphed.
*y varies directly as x- gives the formla y=kx for variation constant, k.
*Directly proportional- means the same as varies directly.
*Fixed cost- a cost that remains.
*Partial variation- the relationship between two variables x and y with the form y=kx + F where k is the constant of variation and F is a fixed number. A partial variation may be represented by a sraight line graph with slope k and which passes through the point (0,F)
*Variable cost- a cost that changes depending upon the amount of goods purchased.
*Vertical intercept- the value where a graph touches or crosses the vertical axis.
*Direct squared variation- a relationship between two variables which can be written in the form y=kx (exponant 2) where k is a constant. The shape of a graph showing this variation will be curved. Te curve will begin at the origin.
*Varies directly as the square- y varies directly as the square of x gives the formula y=kx(exponant 2) with constant of variation, k.
*Inverse variation- a relationship between two variables which can be written in the form y=k/x where k is a contsant. A graph showing this variation decreases as you move to the right along the horizontal axis.