Question

If 5x + 7y=17, 7x+5y=19 then value of x-y is ---------.​

Answer 1

5x + 7y =17 , 7x+ 5y= 19

5x + 7y = 17

7x + 5y = 19

12x + 12y = 36 - -- ( divide by 12)

x + y = 3 --------@ (equation 1 )

5x + 7y = 17

7x + 5y = 19

- - = -

-2x +2y = - 2 -------- ( divide by 2)

-x + y = -1 ---------@ ( equation 2)

therefore ,by adding equation 1 & 2

x /+ y = 3

/-x + y = -1

+2y = 2 ------ (divide by 2 )

y = 1

therefore , adding y = 1 in equation 1 .

x + y = 3

x + 1 = 3

x = 3 - 1

x = 2

Therefore, x - y = ?

= 2 - (-1)

= 2 + 1

= 3

therefore x-y =3.