1.

Solve for x and y:\(\frac{1}{3x+y}+\frac{1}{3x-y}=\frac{3}4\),\(\frac{1}{2(3x+y)}-\frac{1}{2(3x-y)}=-\frac{1}8\)

Answer»

The given equations are

 \(\frac{1}{3x+y}+\frac{1}{3x-y}=\frac{3}4\).........(i)

\(\frac{1}{2(3x+y)}-\frac{1}{2(3x-y)}=-\frac{1}8\)

\(\frac{1}{3x+y}-\frac{1}{3x-y}=-\frac{1}4\) (Multiplying by 2) ……(ii) 

Substituting 1/3x+y = u and 1/3x−y = v in (i) and (ii), we get: 

u + v = 3/4 ……..(iii) 

u – v = − 1/4 …….(iv) 

Adding (iii) and (iv), we get: 

2u = 1/2

⇒ u = 1/4 

⇒3x + y = 4 \((∵\frac1{3x+y}=u)\)........(v)

Now, substituting u = 1/4 in (iii), we get: 

1/4 + v = 3/4 

v = 3/4 - 1/4 

⇒v = 1/2

 ⇒ 3x – y = 2 \((∵\frac1{3x-y}=v)\)....(vi)

Adding (v) and (vi), we get 

6x = 6 ⇒x = 1 

Substituting x = 1 in (v), we have 

3 + y = 4 ⇒y = 1 

Hence, x = 1 and y = 1.



Discussion

No Comment Found