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# AS Further Mathematics FP1 Rational Functions question watch

1. Hi all,

I need help with 5 (b) (i), please. I have tried to find discriminant (D = b^2 - 4ac) but to no avail.

Thank you very much!
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2. (Original post by londoncricket)
Hi all,

I need help with 5 (b) (i), please. I have tried to find discriminant (D = b^2 - 4ac) but to no avail.

Thank you very much!
As you've said we have

Expanding gives us:

So what's the discriminant of this quadratic?

The discriminant of this quadratic would be:

4k^2 - 20k + 16

(Sorry, I am not well versed in LaTeX).
4. (Original post by londoncricket)

The discriminant of this quadratic would be:

4k^2 - 20k + 16
Now you know that that the discriminant should be , since the "intersect" means that there is either one or two solutions.

This gives us . By dividing by .

Could you, perchance - factorise this for me?

(Sorry, I am not well versed in LaTeX).
Don't worry one iota, you're coming across perfectly clear. You do want to press the "reply" button at the bottom-right corner of my post so that I get a notification when you reply to me. :-)
5. (Original post by Zacken)
Now you know that that the discriminant should be , since the "intersect" means that there is either one or two solutions.

This gives us . By dividing by .

Could you, perchance - factorise this for me?

Don't worry one iota, you're coming across perfectly clear. You do want to press the "reply" button at the bottom-right corner of my post so that I get a notification when you reply to me. :-)
That's great. Thanks very much!

I was getting those answers before, but I did not think to factorise the values derived for k, hence not getting it in the form the question wanted it in.

Thanks a tonne for your help! Definitely deserve a rep for this.

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