let's add x+y=10 and x−y=8
2x = 18
x = 9
back in x+y=10, y = 1
now use those values.
(your solution of x=6, y=4
does not satisfy x+y=10 and x−y=8
your x+y = 10, but your x-y=2 , not 8)
What is the value of x^2+y^2?
if x+y=10 and x−y=8
i got 52(x=6, y=4) but its wrong
2 answers
(x+y)^2 + (x-y)^2
= x^2+2xy+y^2 + x^2-2xy+y^2
= 2(x^2+y^2)
...
= x^2+2xy+y^2 + x^2-2xy+y^2
= 2(x^2+y^2)
...