Monday, March 21, 2011

Solve the sistem x^2/y+y^2/x=35/3 x+y=10

To
solve


x^2/y+y^2/x=35/3...(1)


x+y=10..(2).


From
(2), we get  y = 10-x. We put y = 10-x in (1):


x^2/(10-x)
+(10-x)^2/x = 35/3.


3(x^3 +(10-x)^3 ) + 35(10-x)x =
350x-35x^2.


3{x^3+10^3-300x+30x^2-x^3 =
350x-35x^2.


3{1000-300x+30x^2} =
350x-35x^2.


3000-900x+90x^2-350x+35x^2 =
0.


125x^2-1250x+3000 =
0.


x^2-10x+24 = 0.


(x-6)(x-4)
= 0.


So x= 6 or x= 4.


When x =
6, from (2), we get x+y = 10,. So y = 10-6 = 4.


When x=4,
from (2), x+y = 10. So y = 10-4 = 6.


Therefore (x,y) =
(6,4). Or (x,y) = (4,6).

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