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# Help :') Simultaneous Equation with surds. watch

1. Help me with this Simultaneous Equation question:

y=x-4

2x^2 -xy=8

In the form a+- b root 3

Thanks
2. Substitute x-4 into the y place in 2x^2-xy=8

Spoiler:
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Which gives
2x^2-x(x-4)=8
2x^2-x^2+4x=8
x^2+4x-8=0

Then solve the equation using whatever method you like

Warning: you wont learn by just copying. Try first and don't copy it off from my spoiler. If you are still stuck, or you made it but wanna check, look below
Spoiler:
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I'd go for completing the square-
(x+2)^2-4-8=0
(x+2)^2-12=0
(x+2)^2=12
x+2=+/-sqrt12
x+2=+/-sqrt(4*3)
x+2=+/-2sqrt3
x=-2+2sqrt3 or -2-2sqrt3

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Updated: September 24, 2014
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