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Which of these shows a direct variation? How do you know?
Formula
Direct Variation
Inverse
Variation
Joint
Variation
y = kx
Features
• passes through the origin
• As x increases, y increases • When you divide x and y, you get a constant in a direct variation
Formula
Direct Variation
Inverse
Variation
Joint
Variation
Features
y = kx
• Passes through the origin
• Graphs a straight line
• As x increases, y increases • When you divide x and y, you get a constant in a direct variation
y = k
x
• Does not cross the x­axis
• Graphs a curve
• y is said to vary proportionately with x
• As x increases, y decreases • When you multiply x and y, you get a constant in an inverse variation
5.
6.
7.
8.
Formula
Direct Variation
Inverse
Variation
Joint
Variation
Features
y = kx
• Passes through the origin
• Graphs a straight line
• As x increases, y increases • When you divide x and y, you get a constant in a direct variation
y = k
x
• Does not cross the x­axis
• Graphs a curve
• y is said to vary proportionately with x
• As x increases, y decreases • When you multiply x and y, you get a constant in an inverse variation
z = kxy
• When a quantity VARIES DIRECTLY with the product of two (or more) other quantities Write an equation for the relationship:
1. m varies jointly with n, p, and q.
2. x varies inversely with the cube of y.
3. a varies jointly with x and y and inversely with m.
4. t varies directly with u and inversely with w.