Solve for x and y in the equations below
x2 - y2 = 4
x + y = 2
A.
x = 0, y = -2
B.
x = 0, y = 2
C.
x = 2, y = 0
D.
x = -2, y = 0
Correct Answer: x = 2, y = 0
Explanation
x2 - y2 = 4 .... (1)
x + y = 2 .... (2)
Simplify eqn (1)
(x + y)(x - y) = 4
From eqn (2)
x + y = 2 so substitute it into simplified eqn (1), we have
2 (x - y) = 4
therefore,
x - y = 2 ... (1)
x + y = 2
---------
2x = 4
---------
x = 2, when y = 0
x2 - y2 = 4 .... (1)
x + y = 2 .... (2)
Simplify eqn (1)
(x + y)(x - y) = 4
From eqn (2)
x + y = 2 so substitute it into simplified eqn (1), we have
2 (x - y) = 4
therefore,
x - y = 2 ... (1)
x + y = 2
---------
2x = 4
---------
x = 2, when y = 0
