Germany | Can you solve this? | Math Olympiad

[@SuperMario-zt7fl]

We made these in high school and I was never good at maths, so I don't believe that they put these simple exercises at math Olympiads

[@SuperMario-zt7fl]

X1+y1=7
3,5-✓21/2+3,5+✓21/2=7
For x2+y2=7
3,5+✓21/2+3,5-✓21/2=7

[@SuperMario-zt7fl]

X=7-y
Then xy=7
(7-y)y=7
7y-y^2=7
Y^2-7y+7=0
D=b^2-4ac
B=7,a=1,c=7
D=(-7)^2-4*1*7
D=49-28=21
Y={-b(+-)✓d}/2a
Y={7(+-✓21)}/2*1
Y1={7+✓21)}/2
Y2={7-✓21)}/2
For y1 then x=7-y
X=7-(7+✓21)/2
X=3,5-✓21/2
For y2 then x=7-(7-✓21)/2
X=3,5+✓21/2

[@Grizzly01-vr4pn]

Math olympiad? OK then...