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The function, $f(x)=x^2-x-2$ gives me the below graph image 1

But, in a text book for the same equation, they have given different graph. Which one is correct?

Text book graph - (i tried with ms paint, could not get perfectly the curve)...the points are as below,

Image 2

Curve: $(-2,4),(-1,1),(0,0),(1,1),(2,4)$ Line: $(0,2),(1,3),(-1,1),(2,4),(-2,0)$

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    use Wolfram alpha to plot your function – 2017-01-20

2 Answers 2

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No they both are different graphs.

First with parabola y = $\left(x - \frac12 \right)^2 - \frac94$

Second graph with parabola y = $x^2$

and line y = x + 2.

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    @Kanwalijit Singh The given equation is, x^2-x-2=0, So which one should i have to draw? – 2017-01-20
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    First graph is correct. – 2017-01-20
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    Let me explain you one point in graph is (-1,0). As we put x=-1 we get y=0. Other point is (2,0) as we put x=2 we get y=0. So first graph. – 2017-01-20
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    Clear or have some doubt. – 2017-01-20
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    Thanks. Are the x values are picked randomly – 2017-01-20
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    Yes you can but try to avoid fraction values. – 2017-01-20
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The first is a plot of the curve $y=x^2-x-2$, with the intent to show the roots.

The second is a plot of the parabola $y=x^2$ and the straight line $y=x+2$, with the intent to show the intersections.

enter image description here

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    Do you mean to say, both are correct? – 2017-01-20
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    @raman What do you mean by "correct" ? – 2017-01-20
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    can i write any one of the above graph in exam? – 2017-01-20
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    @Raman: yes, provided you understand what they mean (which I doubt a little). – 2017-01-20