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Quadratics help???

kitkat132000

The quadratic equation x^2+ 2kx + 2(k + 4) = 0 has distinct real roots. Show that k^2 – 2k – 8 > 0.

Reply 1

RDKGames

Study Forum Helper

Original post by kitkat132000

The quadratic equation x^2+ 2kx + 2(k + 4) = 0 has distinct real roots. Show that k^2 – 2k – 8 > 0.

The discriminant is greater than 0 for 2 distinct roots.

Reply 2

AlexOD

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By applying the discriminant, b^2-4ac...

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(2k)^2-4(1)(2k+8)>0

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Can you do the rest?

(edited 7 years ago)

Reply 3

RDKGames

Study Forum Helper

Original post by AlexOD

Full Solution

Yeah easy-peasy but full solutions are not allowed on this forum. :smile:

(edited 7 years ago)

Reply 4

AlexOD

Oh sorry

I didn't know that...

Reply 5

kitkat132000

Ok thanks! So is the answer 34>0 which proves that the quadratic is greater than 0.

Reply 6

RDKGames

Study Forum Helper

Original post by kitkat132000

Ok thanks! So is the answer 34>0 which proves that the quadratic is greater than 0.

If you're given a particular value of k to test and it turns out to be 34 on the LHS, then yes. If not, then you simply need to arrive at the required answer without doing anything else. Just saying this as I do not know where you pulled the 34 from.