Question

if 3x - 5y = 9 and 5x+3y=7 find value of x+y​

Answer 1

3x+5y=9-----(1)

5x+3y=7-----(2)

multiplying eq(1) by 5 & eq(2) by 3 we get

15x+25y=45

-15x ± 9y= - 21

_____________

    16y=24

y=  

16

24

​  

=  

2

3

​  

 

[y=  

2

3

​  

] and  x=  

3

9−5x  

2

3

​  

 

​  

=  

2

−1

​  

 

Hence[x=  

2

1

​  

]& [y=  

2

3

​  

]

so x+y=  

2

1

​  

+  

2

3

​  

=2Answer:

Step-by-step explanation:

Answer 2

Answer:

0

Step-by-step explanation:

if we add the equation 1 and 2 we get 8x - 2y = 16 ----- eq 3

and if we subtract eq 2 from 1 we get 2x - 8y = 16 ------ eq 4

8x -2y = 16 can be written as 4x - y = 8

and 2x - 8y = 16 can be written as x - 4y = 8

equating 3 and 4 equations

4x - y = x - 4y

3x + 3y = 0

x + y = 0