Maths Question

C1 solomon paper L
says 1 real root is that the same as two equal roots
Question 3a

https://doc-10-5g-docs.googleusercontent.com/docs/securesc/ha0ro937gcuc7l7deffksulhg5h7mbp1/0umghu0ftihi9gcrgobfmvaiu2nsh1i7/1460577600000/01042298237316186224/*/0B1ZiqBksUHNYejRXVmtoc0I3azg

Also for 6b I got the answer like this:
gradient of m=2/5
y-y1=2/5(x-x1)
5y-5y1=2x-2x1
2x-5y+(-2x1+5y1)

this part will just be a number
so k=-5

(edited 8 years ago)

Reply 1

B_9710

Original post by Acrux

You tend to say that there are equal roots if the discriminant is 0. So there are 2 equal roots to this quadratic.

Reply 2

LewisClothier

Original post by Acrux

C1 solomon paper L
says 1 real root is that the same as two equal roots
Question 3a

In reference to 3)a) The only way to have one real root in a quadratic is if the root is repeated, am i right in saying you worked out that the discriminant of f(x) was equal to 0?

Also, did you have a problem with 6b or are you just saying what you got?

(edited 8 years ago)

Reply 3

Zacken

Original post by Acrux

so k=-5

This is fine and correct.

Reply 4

Acrux

Original post by B_9710

You tend to say that there are equal roots if the discriminant is 0. So there are 2 equal roots to this quadratic.

So it is correct, just that mark scheme says 1 real root
discriminant = 0

Also can some check the other problem in OP 6b - Okay thanks @Zacken

(edited 8 years ago)

Reply 5

Zacken

Original post by Acrux

So it is correct, just that mark scheme says 1 real root
discriminant = 0

Also can some check the other problem in OP

Yes.

Can you check my post?

Reply 6

Acrux

Original post by Zacken

Yes.

Can you check my post?

Yes.
Is part one correct in saying two equal roots mark scheme says 1 equal root.. dont want to drop easy marks

Reply 7

Zacken

Original post by Acrux

Yes.
Is part one correct in saying two equal roots mark scheme says 1 equal root.. dont want to drop easy marks

Yeah, they both basically mean the same thing. Although saying 1 equal root is nonsensical. You either say 1 real/real and repeated root or two equal real roots.

(edited 8 years ago)

Reply 8

Acrux

Original post by Zacken

Yeah, they both basically mean the same thing. Although saying 1 equal root is nonsensical. You either say 1 real root or two equal real roots.

Thanks.

Reply 9

LewisClothier

Original post by Acrux

Yes.
Is part one correct in saying two equal roots mark scheme says 1 equal root.. dont want to drop easy marks

Are you sure it said 1 equal root? not 1 repeated root?

Reply 10

Acrux

Original post by LewisClothier

Are you sure it said 1 equal root? not 1 repeated root?

Yes I meant 1 real root not 'equal'

Reply 11

LewisClothier

Original post by Acrux

Yes I meant 1 real root not 'equal'

okay yeah that makes more sense, I'd say if it's a question that is asking for a quantity or a number of roots and you know that the discriminant is zero, always put 1 to show you know what that means, it is unlikely that moderators would look at whether or not you said equal/repeated etc. They will simply see if you put 0, 1 or 2 and mark correct for 1, so to be sure I'd always write 1 real root there.