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# C1 Exam Question WJEC watch

1. 2008 15th of May C1 paper

10) ii) The curve C has equation y = 3x^2 - 4x + 7. The line L has the equation
y = 2x + k, where k is a constant. Given that L and C do not intersect, find the range of possible values of k.

Any help?

Will rep.

Thanks.
2. Equate the curve and line, rearrange to form a quadratic equation.
Since they don't intersect, what does that tell you about the solutions of the quadratic and it's discriminant...?
3. 3x^2 -6x + (7-k) = 0
Discriminant = 36 - 4x3x(7-k)
36 - 4x3x(7-k) < 0
36 < 84 - 12k
- 48 < -12 k
12k < 48
k < 4
4. First make the equation of the line equal to the quadratic, so 3x^2-4x+7=2x+k.
Then rewrite as 3x^2-6x+7-k=0

The discriminant is (36-12(7-k)) and for no solutions, the discriminant must be negative, so

36<12(7-k)
3<7-k
k<4
5. Wtf why have I been thumbed down?
6. (Original post by joe3469)
Wtf why have I been thumbed down?
There's no reason why you should have been, your maths is right
7. (Original post by jameswhughes)
There's no reason why you should have been, your maths is right
Lol oh well
8. (Original post by jameswhughes)
There's no reason why you should have been, your maths is right
I second this.
9. (Original post by Tempa)
2008 15th of May C1 paper

10) ii) The curve C has equation y = 3x^2 - 4x + 7. The line L has the equation
y = 2x + k, where k is a constant. Given that L and C do not intersect, find the range of possible values of k.

Any help?

Will rep.

Thanks.
Here you go, just have the mark scheme

Enjoy
Attached Images
10. June08.pdf (847.7 KB, 100 views)

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