Excuse me.

[livid moth]

I need help in this problem
x+y=10
xy=40
x=? y=?
Please! I've even tried decimals!

[tall spear]

x and y are clearly not zero so you can substitute y = 40/x in the first equation and solve for x

[livid moth]

ok so 40y=x

[tall spear]

no

40/y

[glossy hatch]

the roots will be complex

[livid moth]

Oh really??

[glossy hatch]

yes

[gray nacelle]

y=10-x.
x(10-x)=40
10x-x^2=40
x^2-10x+40=(x-5)^2+40-25
x-5=-+ sq(15)i
x=5-+sq(15)i

[glossy hatch]

so 5 + root 15 i
and 5 - root 15 i

as b^2-4ac is -ve

so D is negative

[livid moth]

It has to be on the complex plane!

keyword "has"

Thanks for your help, I really appreciate it!

It is solved!

[sullen bone]

Let me see

......