Respuesta :

9514 1404 393

Answer:

  (x, y) = (1/2, 1)

Step-by-step explanation:

Subtract twice the second equation from the first to eliminate the x-variable.

  (2/x +3/y) -2(1/x -4/y) = (7) -2(-2)

  11/y = 11 . . . . . . . simplify

  y = 1 . . . . . . . . multiply by y/11

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Substituting into the second equation gives ...

  1/x -4/1 = -2

  1/x = 2 . . . . . . add 4

  1/2 = x . . . . . . multiply by x/2

The solution is (x, y) = (1/2, 1).

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Additional comment

The attached graph seems to show that the graphs of the two equations also intersect at (x, y) = (0, 0). However, careful consideration of these equations leads to the conclusion that x=0 and y=0 are not in the domain of either equation. (Division by 0 is undefined.) So, the only solution is (x, y) = (1/2, 1).

If you were to multiply both equations by xy to eliminate fractions, you would, indeed, arrive at the conclusion that (x, y) = (0, 0) is a solution. As we noted, that "solution" is extraneous. Whenever you multiply an equation by an expression that can have the value 0, you need to be careful to exclude any "solution" that makes that expression 0.

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