If x varies inversely as y and x=2.5 when y = 40 , find y when x = 2
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Answer:
(6, - 4 )
Step-by-step explanation:
Given the 2 equations
-
y = 3 → (1)
x -
= 12 → (2)
Multiply (1) by 8 and (2) by 6 to clear the fractions
2x - 3y = 24 → (3)
10x - 3y = 72 → (4)
Rearrange (3) expressing - 3y in terms of x by subtracting 2x from both sides
- 3y = 24 - 2x
Substitute 3y = 24 - 2x into (4)
10x + 24 - 2x = 72, that is
8x + 24 = 72 ( subtract 24 from both sides )
8x = 48 ( divide both sides by 8 )
x = 6
Substitute x = 6 in either (3) or (4) and solve for y
Substituting in (3)
2(6) - 3y = 24
12 - 3y = 24 ( subtract 12 from both sides )
- 3y = 12 ( divide both sides by - 3 )
y = - 4
Solution is (6, - 4 )