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#1
Why did they use p^2 / 4 - 4 < 0 to find no real roots? I just applied the discriminant directly to the quadratic equation and got the same answer, can anyone shed some light on this weird alternate method?

I'm looking at Q3b
Last edited by GogetaORvegito?; 1 month ago
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#2
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1 month ago
#3
(Original post by GogetaORvegito?)
Why did they use p^2 / 4 - 4 < 0 to find no real roots? I just applied the discriminant directly to the quadratic equation and got the same answer, Can anyone shed some light on this weird alternate method?

I'm looking at Q3b
They also did simply apply the discriminant condition.
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1 month ago
#4
Yh I woulda done p^2 - 16 < 0. Essentially they’ve done that but then just divided everything by 4, hence the first line. Same thing tho
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#5
(Original post by Otherdjrj)
Yh I woulda done p^2 - 16 < 0. Essentially they’ve done that but then just divided everything by 4, hence the first line. Same thing tho
Yeah kinda weird how they went the extra mile and divided everything by 4
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#6
(Original post by RDKGames)
They also did simply apply the discriminant condition.
Oh ok lol. They just thew me off by going the extra mile and dividing by 4
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1 month ago
#7
(Original post by GogetaORvegito?)
Why did they use p^2 / 4 - 4 < 0 to find no real roots? I just applied the discriminant directly to the quadratic equation and got the same answer, can anyone shed some light on this weird alternate method?

I'm looking at Q3b
Because if you do the question in order, part (a) automatically gives you the quantity (p^2/4) - 4 as the constant which the square ,must be equal to. So if this is < 0 you can see immediately that there are no real roots
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#8
(Original post by davros)
Because if you do the question in order, part (a) automatically gives you the quantity (p^2/4) - 4 as the constant which the square ,must be equal to. So if this is < 0 you can see immediately that there are no real roots
Oh I thought about how maybe the used that and equated that to zero when they put it on the other side of the square. But I just thought why would that be less than zero if the whole equation is different now
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