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AS Maths: how do I get this answer? watch

1. Right so, we're studying the discriminant zero equation and I plodded through the questions until I got to the last one.

Here is it:

Q) If is negative and is positive, what can be said about the graph of ?

The graph will bend upwards and intersect the x axis twice.

I can kind of understand the answer but can't; I can see why it bends upwards since it is a positive graph but why does it intersect the x axis twice?

Please could somebody explain, as nooby as this question is
2. its basically a U (an upside down parabola) so its intersects the x-axis twice as it is x^2 and as it is -c, then it will cross the y-axis at the negative bit
3. (Original post by Dededex)
Right so, we're studying the discriminant zero equation and I plodded through the questions until I got to the last one.

Here is it:

Q) If is negative and is positive, what can be said about the graph of ?

The graph will bend upwards and intersect the x axis twice.

I can kind of understand the answer but can't; I can see why it bends upwards since it is a positive graph but why does it intersect the x axis twice?

Please could somebody explain, as nooby as this question is
does it say anything about b??
I would think you need to complete the square or consider the discriminant.
4. Because is positive therefore it will intersect the graph twice.
5. (Original post by watchthis)
its basically a U (an upside down parabola) so its intersects the x-axis twice as it is x^2 and as it is -c, then it will cross the y-axis at the negative bit
wouldn't it be ∩-shaped?

in the equation
since "c" = -c, D can never be less than b^2 which is larger than 0. So the equation y=0 always has 2 roots.
6. (Original post by Dededex)
Right so, we're studying the discriminant zero equation and I plodded through the questions until I got to the last one.

Here is it:

Q) If is negative and is positive, what can be said about the graph of ?

The graph will bend upwards and intersect the x axis twice.

I can kind of understand the answer but can't; I can see why it bends upwards since it is a negative graph but why does it intersect the x axis twice?

Please could somebody explain, as nooby as this question is
Fixed

(And someone mentioned you can use the discriminant for it cutting the x axis twice)
7. (Original post by 808)
wouldn't it be ∩-shaped?

in the equation
since "c" = -c, D can never be less than b^2 which is larger than 0. So the equation y=0 always has 2 roots.
yes, could be, but I always thought what determined whether the graph is a parabola or an upside down parabola was always whether ax^2 was positive or negative.

yes, in fact it would be a parabola. my mistake as a is negative, didnt read the question ;p

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