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discriminant alevel maths

I can do the easier question but when they start adding more letter I am unable to do them
Does anyone have any advice?
Reply 1
Avatar for _ks233
_ks233
11
can you give me an example?
Learn English before Maths.
Original post by louise18152
I can do the easier question but when they start adding more letter I am unable to do them
Does anyone have any advice?


Do you mean something like when they add another constant that you need to find? Please give the specific question that is causing you problems
Reply 4
Avatar for ymca_m
ymca_m
20
Do you have any examples?
Reply 5
Avatar for louise18152
louise18152
OP
9
sorry yeah
2x^2+(3-k)x+k+3 and it's two distinct roots
I got to k^2-2k-15>0
but I don't know if that's right
(edited 3 years ago)
Original post by louise18152
sorry yeah
2x^2+(3-k)x+k+3 and it's two distinct roots

so you would just sub a=2, b=(3-k) and c=(k+3) in to the equation. And you said it's got two distinct roots so it's greater than 0
Reply 7
Avatar for _ks233
_ks233
11
Original post by louise18152
sorry yeah
2x^2+(3-k)x+k+3 and it's two distinct roots

a = 2
b = 3-k
c = k+3

b^2 -4ac >0

(3-k)^2 - (4)(2)(k+3) > 0
K^2 -6k +9 - (8)(k+3) >0
k^2-6k+9 -8k -24 >0
k^2 -14k -15 >0
k< -1 , 15<k
Reply 8
Avatar for louise18152
louise18152
OP
9
Original post by ItsStarLordMan
so you would just sub a=2, b=(3-k) and c=(k+3) in to the equation. And you said it's got two distinct roots so it's greater than 0

I just edited it can you check that
Original post by _ks233
a = 2
b = 3-k
c = k+3

b^2 -4ac >0

(3-k)^2 - (4)(2)(k+3) > 0
K^2 -6k +9 - (8)(k+3) >0
k^2-6k+9 -8k -24 >0
k^2 -14k -15 >0
k< -1 , 15<k

yep yep yep :smile:
Original post by _ks233
a = 2
b = 3-k
c = k+3

b^2 -4ac >0

(3-k)^2 - (4)(2)(k+3) > 0
K^2 -6k +9 - (8)(k+3) >0
k^2-6k+9 -8k -24 >0
k^2 -14k -15 >0
k< -1 , 15<k

where is the - 1 and 15 from
Original post by louise18152
where is the - 1 and 15 from

They factorised it
oh ok thanks for your help

Original post by ItsStarLordMan
They factorised it
Original post by louise18152
oh ok thanks for your help

ofc. You get it all noow?
yeah do you know of any good websites for revision
Original post by louise18152
yeah do you know of any good websites for revision

seneca, snaprevise, ixl, khanacademy xx
i PMed you :smile:

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