Posted by tara on Thursday, October 28, 2010 at 8:35pm.
xy = 1,
4x - y + 3 = 0.
Solve 1st Eq for x:
X = 1/y,
Substitute 1/y for x in EQ2:
4/y - y + 3 = 0,
Multiply both sides by -y:
-4 + y^2 - 3y = 0,
y^2 - 3y - 4 = 0,
Factor the trinomial:
(y + 1) (y - 4) = 0,
y + 1 = 0,
y = -1.
y - 4 = 0,
y = 4.
Substitute -1 for y in Eq1:
x*-1 = 1,
x = -1.
Substitute 4 for y in Eq1:
x * 4 = 1,
x = 1/4.
Solution set: (-1 , -1) , (1/4 , 4).