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silverangel's avatar

A math question... help?

Asked by silverangel (939points) October 3rd, 2011

There is this Algebra problem that I don’t understand how to solve. Here it is:
Find the coordinates of the points at which the line with the equation y=x-4 intersects the curve with equation Y 2 =2X 2 -17

I already have the solution which is (-11,-15) and (3,-1) but I don’t know how to get, can you help me please?

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5 Answers

Mariah's avatar

I can help you but first can you clarify something for me? Do you intend Y 2 and X 2 to mean Y/X squared or just a subscript 2? I know that Fluther formatting doesn’t always make writing math problems very easy. Thanks.

silverangel's avatar

they are squared

Mariah's avatar

Oh okay, thanks!
We’re not supposed to tell people exactly how to do their homework here on Fluther but I can point you in the right direction.

Points of intersection occur at points where a certain value (x,y) satisfies both equations. That is, you want the y’s in both equations to be the same and you want the x’s in both equations to be the same. So, you can go about it by setting the y value in the first equation, x-4, equal to the y value in the second equation, sqrt(2x^2 – 17).

So start with x-4 = sqrt(2x^2 – 17). Can you solve it from there? I can help you more if you can’t.

silverangel's avatar

Thanks so much, it did help a lot, I figured I had put the wrong signs.
I solved it as positive 4 rather than negative, that’s why I got it wrong
Many thanks once again ;-)

Mariah's avatar

Great! You’re welcome. :)

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