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That would be a quadratic expression which describes a parabola. You can find where it intersects the x-axis by solving it for zero:

x2 + 2x - 7 = 0

x2 + 2x + 1 = 8

(x + 1)2 = 8

x + 1 = ± 2√2

x = -1 ± 2√2

This tells us that it intersects the x-axis at the points where x equals -1 + 2√2 and -1 - 2√2.

If you'd like to find it's vertex, you can check that easily by taking it's derivative with respect to x and solving that for zero:

y = x2 + 2x - 7

y' = 2x + 2

Let y' = 0:

0 = 2x + 2

2x = -2

x = -1

So we know that the vertex of this parabola is at the point where x = -1.

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Q: What is Xsquared plus 2X-7 equals 0?
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