# Questions for exam tomorrow

• Jan 8th 2009, 10:04 AM
Ifailatmaths
Questions for exam tomorrow
C1 exam tormorrow, got some last minute questions.

5.The equation $\displaystyle 2x^2 -3x - (k + 1) = 0$, where k is a constant, has no real roots.

Find the set of possible values of k.

So I use $\displaystyle b2-4ac<0$?

If the question said:

5.The equation $\displaystyle 2x^2 -3x - (k + 1) = 0$, where k is a constant, has equal roots.

I would use: $\displaystyle \sqrt b2-4ac=0$?

And if the question said

5.The equation $\displaystyle 2x^2 -3x - (k + 1) = 0$, where k is a constant, 2 real roots.

I would use: $\displaystyle b2-4ac>0$?
• Jan 8th 2009, 10:12 AM
running-gag
Hi

Yes that's it
For the second example you made a typing error : $\displaystyle b^2 - 4ac = 0$
• Jan 8th 2009, 10:13 AM
Last_Singularity
Quote:

Originally Posted by Ifailatmaths
C1 exam tormorrow, got some last minute questions.

5.The equation $\displaystyle 2x^2 -3x - (k + 1) = 0$, where k is a constant, has no real roots.

Find the set of possible values of k.

So I use $\displaystyle b2-4ac<0$?

If the question said:

5.The equation $\displaystyle 2x^2 -3x - (k + 1) = 0$, where k is a constant, has equal roots.

I would use: $\displaystyle \sqrt b2-4ac=0$?

And if the question said

5.The equation $\displaystyle 2x^2 -3x - (k + 1) = 0$, where k is a constant, 2 real roots.

I would use: $\displaystyle b2-4ac>0$?

Precisely (Clapping)
• Jan 8th 2009, 10:16 AM
Ifailatmaths
Quote:

Originally Posted by running-gag
Hi

Yes that's it
For the second example you made a typing error : $\displaystyle b^2 - 4ac = 0$

Typing error I thought I used a square root when its equal roots?
• Jan 8th 2009, 10:18 AM
running-gag
I only meant that you wrote $\displaystyle \sqrt b2-4ac=0$ instead of $\displaystyle b^2-4ac=0$
• Jan 8th 2009, 10:19 AM
Ifailatmaths
Quote:

Originally Posted by running-gag
I only meant that you wrote $\displaystyle \sqrt b2-4ac=0$ instead of $\displaystyle b^2-4ac=0$

Ah gotcha, cheers.