Question

Solve 9x + 7y = 55 , 7x + 9y = 57 by Elimination Method​

Answer 1

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We have

9x + 7y = 55

7x + 9y = 57

You see the pair of Equation is in the form

ax + by = c

bx + ay = d

Thus a = 9 , b = 7 , c = 55 and d = 57

See this is the method you'll not find anywhere else

Thus x - y = -1-----(1)

Similarly

x + y = 112/16

=> x + y = 7-----(2)

Add (1) and (2)

=> x + y + x - y = 7 - 1

=> 2x = 6

=> x = 3

Using x in (2)

=> x + y = 7

=> y = 4

Thus x = 3 and y = 4

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Hope this helps ✌️

Using the simple method of elemination , we get

9x+7y=55

+ 7x+9y=57

16(x+y) = 112

x+y=7 eq1

Now reducing x, we get

9x+7y=55

- 9x+9y=63

-2y = -8

y = 4 ...eq2

Putting value of y in eq1, we get

x= 3

so, x=3 and y=4.

Answer 2

Explanation:

9x+7y=55. (1)

7x+9y=57. (2)

add equation (1) and (2),

16 x+16y=112.

16(x+y)=112

x+y=7. (3)

subtract equation (2). from (1)

2x-2y= -2

2(x-y)= -2

x-y= -1. (4)

add equation (3)& (4),

2x=6

x=3

put value of x in equation 3,

3+y=7

y=4

hence x= 3 and. y=4