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1. I know the method but have spent ages wondering why I can't get the right values in the simultaneous equation:
y=3x-1
x^2-y^2+12x=0

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2. You know that

therefore, substitute that into to get a quadratic in (since you have in terms of ), and solve as you would solve a quadratic normally. Then, once you've ascertained , substitute that into

to find the corresponding value(s).
3. Do you know what the answers are supposed to be? Also does the answer have to be whole?

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4. I know that's the method but it is a non calculator question and I am assuming the answer is relatively basic numbers, I end up with the simplified quadratic -8x^2+6x+1=0, is this correct by this stage?

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I know that's the method but it is a non calculator question and I am assuming the answer is relatively basic numbers, I end up with the simplified quadratic -8x^2+6x+1=0, is this correct by this stage?

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Therefore,

Substituting into as the :

Solve from there.
I know that's the method but it is a non calculator question and I am assuming the answer is relatively basic numbers, I end up with the simplified quadratic -8x^2+6x+1=0, is this correct by this stage?

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yep that's what I get, now just quadratic formula both of them and plug both answers back into the original y=3x-1 .
7. You should get:
When x = 2.193, y = 5.579
When x = 0.057, y=-0.829

It depends on how you round it because you have to use the quadratic formula.
I know that's the method but it is a non calculator question and I am assuming the answer is relatively basic numbers, I end up with the simplified quadratic -8x^2+6x+1=0, is this correct by this stage?

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Bring all the terms on the other side so that it becomes positive rather than negative. It makes things much more easier. So you should get 8x^2-18x+1. It's 18x because 6x +12x =18x. Be careful of your signs.
9. Or do you just want me to show you the whole working out?
10. You should get 8x^2-18x+1=0 and from there, use the x=(-(b)^2± √(b)^2-4(ac))/2(a) formula to get the values of x, then substitue back into any equation of your choice to get the y values

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11. (Original post by Brainiac_98)
You should get 8x^2-18x+1=0 and from there, use the x=(-(b)^2± √(b)^2-4(ac))/2(a) formula to get the values of x, then substitue back into any equation of your choice to get the y values

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Yeah, exactly!

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Updated: July 10, 2014
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