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Harder 2U Qs : Quadratic Polynomial (1 Viewer)

Tsylana

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Well i stumbled across this question and im not sure if i'm doing it right or not because i keep getting really strange answers.... ><"

The question goes Find the relationship between a and b in the equation ax^2 + bx + c = 0 ; When the larger root exceeds the smaller root by 1.

><"

Thanks guys =].
 

lyounamu

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Tsylana said:
Well i stumbled across this question and im not sure if i'm doing it right or not because i keep getting really strange answers.... ><"

The question goes Find the relationship between a and b in the equation ax^2 + bx + c = 0 ; When the larger root exceeds the smaller root by 1.

><"

Thanks guys =].
Let the roots be @ and @+1.

@ + @+1 = -b/a
2@ + 1 = -b/a
-2a@ - a = b
b= -2a@ - a

Like this?
 
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Tsylana

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errr o__O". ok lol. now i feel like a dumbass... ><"

would i need to find the alpha term and sub it into that equation?
 
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lyounamu

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Tsylana said:
errr o__O". ok lol. now i feel like a dumbass... ><"

would i need to find the alpha term and sub it into that equation?
No. Alpha is one of the roots that is unknown. Alpha can be anything.
 

Tsylana

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hmmm but if

2alpha + 1 = -b/a

then can't you do this


alpha =(-b/a - 1)/2

and sub it into that equation you just wrote?
 

lyounamu

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Tsylana said:
hmmm but if

2alpha + 1 = -b/a

then can't you do this


alpha =(-b/a - 1)/2

and sub it into that equation you just wrote?
If you do that, you will get b = b. That way, you don't show the relationship between a & b.
 

Tsylana

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hmm something just doesn't seem right with this question ><"

the follow on questions "The roots are in ratio of 2:3" and it asks the same thing... ><" it seems too easy to be considerred "Harder 2U Qs" but oh well... this is like damaging my brain haha ><" makes me feel so stupid and smart and the same time -.-"
 

foram

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Tsylana said:
hmm something just doesn't seem right with this question ><"

the follow on questions "The roots are in ratio of 2:3" and it asks the same thing... ><" it seems too easy to be considerred "Harder 2U Qs" but oh well... this is like damaging my brain haha ><" makes me feel so stupid and smart and the same time -.-"
Harder 2U isn't supposed to be very hard.
 

tommykins

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ax^2 + bx + c = 0

Roots are 2@:3@

5@ = -b/a

a5@ = -b
b = -a5@
 

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