Question

x+y=9 , y+x=18 find x and y ​

Answer 1

Heya Mate.......

x+y=9………(1)

y+x=18………(2)

Now equⁿ(2)

x-y=18………(3)

Now equⁿ(1)&(3)add

x+y=9

+x-y=18

2x = 27

x=27/2

x=13.5

Now put x=13.5 in equⁿ(1)

x+y=9

13.5+y=9

13.5-9=-y

4.5 =-y

y=-4.5

Hope this will help you.......

Answer 2

So,

xy = 18, therefore x = 18/y

18/y + y = 9

18 + y^2 = 9y

On rearranging, we get

y^2 - 9y + 18 = 0

Solving the quadractic equation:

y^2 - 3y - 6y + 18 = 0

y(y-3) - 6(y-3) = 0

(y-6)(y-3) = 0

Therefore, y = 6 or y = 3

So if y = 6, x = 3

and if y = 3, x = 6