Answers

2015-09-13T10:29:24+08:00
-14 is the correct answer.Because -18/9 = -2 so 7 x -2 = -14

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how about this if y = 2.5 when x =.25, find when x =.75
.75/.25 = 3,then 3 x 2.5 = 7.5. 7.5 is the answer.
ahhh okey.
(y / y) * x = n.
nice! youre a genius
  • Brainly User
2015-09-13T15:09:50+08:00
The problem does not state the type of variation.  If it's a direct variation, then it's like proportion problems.  

Assuming it's a direct variation:
y varies directly with x.  If y = -18 when x = 9, find y when x = 7.

y = kx
 -18 = k (9)
 -18/9 = k (9)/9

-2 = k, constant of direct variation.

To solve for y, use the constant of variation, -2 when x = 7
y = -2(7)
y = -14, final answer.

Assuming it's an inverse variation:
y varies inversely with x.  If y = -18 when x = 9, find y when x=7.

y = k/x
-18 = k/9
k = (9) (-18)
k = -162, the constant of inverse variation

Using the constant -162 for y = ? when x = 7
y = k/x
y = -162/7

y = -162/7 or -23 1/7

See the difference in y values?



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