EXAMPLE 1 Identify direct and inverse variation Tell
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EXAMPLE 1 Identify direct and inverse variation Tell whether the equation represents direct variation, inverse variation, or neither. a. xy = 4 SOLUTION xy = 4 y= 4 x Write original equation. Divide each side by x. Because xy = 4 can be written in the form y = ax , xy = 4 represents inverse variation. The constant of variation is 4.
EXAMPLE 1 Identify direct and inverse variation Tell whether the equation represents direct variation, inverse variation, or neither. y b. =x 2 SOLUTION y =x 2 y = 2 x Write original equation. Multiply each side by 2. y y Because 2 = x can be written in the form y = ax, 2 = x represents direct variation.
EXAMPLE 1 Identify direct and inverse variation Tell whether the equation represents direct variation, inverse variation, or neither. c. y = 2 x + 3 SOLUTION a Because y = 2 x + 3 cannot be written in the form y = x or y = ax, y = 2 x + 3 does not represent either direct variation or inverse variation.
GUIDED PRACTICE for Example 1 Tell whether the equation represents direct variation, inverse variation, or neither. 2 1. y = x ANSWER inverse variation
GUIDED PRACTICE 2. 4 y = 3 x ANSWER direct variation for Example 1
GUIDED PRACTICE 3. 5 x – y = 3 ANSWER neither for Example 1
GUIDED PRACTICE 4. xy = 1 2 ANSWER inverse variation for Example 1
