Monday, November 10, 2014

Verify if the lines are intercepting? y = (5-x)/(1+x) y*x^2+x*y^2=6

We'll multiply the 1st equation by 1+x both
sides:


y*(1+x) = 5-x


We'll
remove the brackets:


y + x*y =
5-x


We'll move all terms to one
side:


y+x + x*y - 5 = 0
(3)


We'll factorize th second equation by
x*y:


x*y(x+y) = 6 (4)


We'll
substitute x+y = S and x*y = P


We'll re-write the equations
(3) and (4):


S+P-5=0 => S =
5-P


S*P=6


(5-P)*P=6


We'll
remove the brackets:


-P^2 + 5P - 6 =
0


P^2  - 5P + 6 = 0


P1 = 1
=> S1 = 5-1=4


P2 = 5 => S2 = 5-5 =
0


x + y = S1 <=> x+y =
4


x*y= P1 <=> x*y =
1


x^2 - Sx + P = 0


x^2 - 4x +
1 = 0


x = [4+sqrt(16-4)]/2


x =
[4+sqrt(12)]/2


x =
(4+2sqrt3)/2


x = 2+sqrt3 ; y =
2-sqrt3


x = 2-sqrt3 ; y =
2+sqrt3


x + y = S2 <=> x+y =
0


x*y= P2 <=> x*y =
5


x^2  + 5 = 0
impossible!


There are no real values of x to satisfy the
equation.


The lines are intercepting in the
points (2+sqrt3 ; 2-sqrt3) and (2-sqrt3 ;
2+sqrt3).

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