#3x^2 - y^2 = 3; color(white)("ddd")(x-1)^2 + y^2 = 4# ?

I know that the answer is (-1, 0) (3/2, sqrt 15/2), and (3/2, -sqrt 15/2)

How?

1 Answer
Dec 5, 2017

#(-1,0) ; (3/2,-sqrt(15)/2); (3/2,+sqrt(15)/2)#

Explanation:

Given:
#3x^2-y^2=3" "........................Equation(1)#

#(x-1)^2+y^2=4" "................Equation(2)#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Determine the values of "x)#

Consider #Eqn(1)#

Write as: #y^2=3x^2-3" "..........Equation(1_a)#

Using #Eqn(1_a)# substitute for #y^2" in "Eqn(2)# giving:

#(x-1)^2color(white)("dddddd")+color(white)("d.")(3x^2-3)=4#

#x^2-2x+1color(white)("ddd")+color(white)("ddd")3x^2-3=4#

#4x^2-2x-2=4#

#4x^2-2x-6=0#

Divide both sides by 2

#2x^2-x-3=0#

#(2x-3)(x+1)=0#

For #2x-3=0color(white)("d")-> color(white)("ddd")x=3/2#

For #x+1=0color(white)("d")->color(white)("ddd")x=-1#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Determine the values of "y)#

#color(brown)("Substitute the value of "x=-1" in "Eqn(1) ) #

#3x^2-y^2=3 color(white)("ddd")->color(white)("ddd")3(-1)^2-y^2=3#

#color(white)("ddddddddddddd")->color(white)("ddd")y=0color(green)(larr" matches the graph")#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(brown)("Substitute the value of "x=+3/2" in "Eqn(1) ) #

#3x^2-y^2=3 color(white)("ddd")->color(white)("ddd")3(3/2)^2-y^2=3#

#color(white)("ddddddddddddd")->color(white)("ddddd")27/4color(white)("d")-y^2=12/4#

#color(white)("ddddddddddddd")->color(white)("ddd")y=+-sqrt(15)/2#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Putting it all together")#

#(-1,0) ; (3/2,-sqrt(15)/2); (3/2,+sqrt(15)/2)#

Tony B