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7 divided by 4 x + 3 Y + 4 divided / 4 x minus 3 Y is equal to 5 / 4


(7 )/(4x + 3y) + (4)/(4x - 3y) = (5)/(4) \\ (8)/(4x - 3y) - (14)/(4x + 3y) = (3)/(2)


User Nigel Ren
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1 Answer

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Answer:

(x, y) = (4, 4)

Explanation:

If you attempt to solve this by clearing fractions, you end up with an extraneous solution. Here, we'll solve the linear equations ...

7a +4b = 5/4

8b -14a = 3/2

where a = 1/(4x+3y) and b = 1/(4x-3y)

Dividing the second equation by 2 and adding the first, we have ...

(7a +4b) +1/2(8b -14a) = (5/4) +1/2(3/2)

8b = 8/4

b = 1/4

Substituting into the first equation gives ...

7a +4/4 = 5/4

a = 1/28

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Now, we can get back to solving for x and y.

4x +3y = 1/a = 28

4x -3y = 1/b = 4

8x = 32 . . . . . . . . . add the two equations

x = 4

3y = 28 -4x = 28 -4(4) = 12 . . . . . use x in the equation for 'a'; rearrange

y = 4 . . . . divide by 3

The solution to the system of equations is (x, y) = (4, 4).

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Additional comment

If you graph these equations, you find they describe hyperbolas that intersect at (0, 0) and (4, 4). The "solution" (0, 0) is extraneous, as both equations are undefined there.

User Grekz
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