x^2 + xy + y62 =
200...............(1)
x + (xy)^1/2 + y =
20...............(2)
First we will re-wrtie equation
(2).
We will move (xy)^1/2 to the right
sides.
==> (x+ y) = 20 -
(xy)^1/2
Now we will square both
sides.
==> (x+ y)^2 = (20- (xy)^1/2)
^2
==> x^2 = 2xy + y62 = 400 - 40(xy)^1/2)
+xy
Now subtract xy from both
sides.
==> x^2 + xy + y^2 = 400 -
40(xy)^1/2)
But, from equation (1) , we know that x^2 + xy
+ y^2 = 200.
==> 200 = 400 -
40(xy)^1/2)
==> -200 =
-40(xy)^1/2
==> (xy)^1/2 = 200/40 =
5
==> xy =
25.............(3)
Now we will substitute in
(1) and (2).
==> x^2 + y^2 + 25 =
200
==> x^2 = y^2 = 175
............(4)
==> x+ 5 + y
20
==> x+ y =
15
==> y= 15-x
...............(5)
Now substitute on
(3)
==> x*y =
25
==> x( 15-x) =
25
==> 15x -x^2 =
25
==> x^2 - 15x + 25 =
0
==> x1=( 15+ 5sqrt5)/2 ==>
y1= ( 15-5sqrt5)/2
==>
x2= (15-5sqrt5) /2 ==> y2= (15+5sqrt5)/2
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