Question

solve the simultaneous equation and write the value of x . 12x +13y =109; 13x+12y=91​

Answer 1

Solution:-

12x + 13y = 109 ...(i) eq

13x + 12y = 91 ...(ii) eq

Now add ( i ) and ( ii ) to get

=> 12x + 13y + 13x + 12y = 109 + 91

=> 25x + 25y = 200

=> 25 ( x + y ) = 200

=> x + y = 8 .....(iii)

Now subtract ( i ) from ( ii ) to get

=> 13x + 12y - ( 12x + 13y ) = 91 - 109

=> 13x + 12y - 12x - 13y = - 18

=> x - y = - 18 ........( iv )

Now using elimination method

Add ( iii )and ( iv ) to get

=> x + y + x - y = 8 - 18

=> 2x = - 10

=> x = - 5

Now put the value of x on (iii) eq

=>x + y = 8

where x = - 5

=> - 5 + y = 8

=> y = 8 + 5

=> y = 13

Answer:- x = - 5 and y = 13