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Solve for x and y:\(\frac{5}{x+y}-\frac{2}{x-y}=-1\),\(\frac{15}{x+y}-\frac{7}{x-y}=10\) |
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Answer» The given equations are \(\frac{5}{x+y}-\frac{2}{x-y}=-1\).......(i) \(\frac{15}{x+y}-\frac{7}{x-y}=10\)......(ii) Substituting 1/x+y = u and 1/x−y = v in (i) and (ii), we get 5u – 2v = -1 ……..(iii) 15u + 7v = 10 …….(iv) Multiplying (iii) by 3 and subtracting it from (iv), we get 7v + 6v = 10 + 3 ⇒ 13v = 13 ⇒ v = 1 ⇒x – y = 1 \((∵\frac{1}{x-y}=v)\)......(v) Now, substituting v = 1 in (iii), we get 5u – 2 = -1 ⇒5u = 1 ⇒u = 1/5 x + y = 5 …….(vi) Adding (v) and (vi), we get 2x = 6 ⇒ x = 3 Substituting x = 3 in (vi), we have 3 + y = 5 ⇒ y = 5 – 3 = 2 Hence, x = 3 and y = 2. |
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