Friday, December 30, 2011

Solve the system of equations algebraically x^2+y^2=100 x-y=2

Given:-


(x^2) + (y^2) = 100
..........(1)


x - y =
2...........(2)


Squaring (2) on both sides we
get


(x-y)^2 = (2)^2


or, (x^2)
+ (y^2) - 2xy = 4


Putting the value of (x^2) + (y^2) from
(1) in the above equation we get


100 - 2xy =
4


or, 2xy =
96...........(3)


Now, (1) + (3)
 gives


(x^2) + (y^2) + 2xy = 100 +
96


or, (x+y)^2 = 196


or,
(x+y)^2 = (14)^2


or, (x+y) =
14.........(4)


or, (x+y) =
-14..........(5)


Now, (2) + (4)
gives


2x = 16


or, x =


Thus, y =
6...........(6)


Also, (2) + (5)
gives


2x = -12


or, x =
-6


Thus, y =
-8..........(7)


Hence the two values of (x,y) are (8,6)
& (-6,-8)

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