OCR MEI Core 1 4.10 Discriminant - Finding values of k for two distinct real roots

[morgue_brat]

Such an underrated guy .You deserve more appriciation, Sir.

[amaankhan]

hi sir, for 2 real roots when 2x^2-(3+k)x+3 = 0, the mark scheme says b^2-4ac > 0 therefore (3+k)^2 -24 > 0, but why have they forgotten the -ve sign in front of the b. Why is it not -(3+k)^2 -24 > 0? thank you

[Londonista]

The question asks for the possbile values of k, not the range

[MrHbx]

hey at around 1:40 you figure out the inequalities which i am having trouble solving for these kinds of questions. for example number 1 you have k^2-16k>0 could this not be further simplified to sqrt(k^2)>16 getting k > +- 4 then progressing from there (if possible how do you progress)?
if not why? how do you find that its going thru the point 0 i understand the 16 as k=16 is a root to the solution. Lastly what do you mean by "where this is above the k axis"? If you have any videos regarding this issues please recommend if available!

Thanks!!

[diyagirishkumar]

What happens if there is a certain condition for the solutions? For example, one solution is within 1<x<2.

[kalihinder]

When you sketch the curve, how do you know if it is x^2 or -x^2? Like you did a "u" shape for one and then an "n" shape for another?

[LeoPatrickSlaterIBAKAGY]

Could you also take 4 and 3 instead of 2 and 6?

[james_harman]

Hi what happens if you end up getting rid of all k in the equation and only left with a single number ?

[lite]

hey Mr Brown, I have a question. why bother multiplying by -1 in the last question. You can easily factorise it -7k^2 + 20k -12 its

(7k-6)(-k-2)>0 and that gives you the same answer you got

[arshmazahoor]

Hi sir, how would I find the discriminant for the equation x^2 - (k+8)x + (8k+1) ?
Would it be:
a= 1
b= - k- 8
c= 8k + 1

[AbdulKadir-gleg]

Mr jack brown i have a question, why in the previous video you multiplied by -1 for one of the equation. but in this video, for q2.) you didn't