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Equation x2 = 2x

For the equation x2 = 2x there are two simple solutions, those are is x = 2 and x = 4. There is another solution, but it is not easy to guess.

 


Explanation

With a bit of dexterity, you'll find the value x = −0,7667…. on a calculator, because

2−0,7667 = 0,587…   and   (−0,7667)2 = 0,587…

where this answer is accurate to three decimal places. The three intersections can be seen in the graph.

I don't know how you calculate this. So let's leave it here. And now, of course, the question: Are there any other solutions?

 


Example 1

You can see that the functions y1 = x2 and y2 = 2x have three points of intersection

x = −0,766666469, x = 2 and x = 4

 


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