Let `u=x^-1`. Then we have:
So `u=1/5 or -1/2`
This gives us `x^-1=1/5` so `x = 5`
and `x^-1=-1/2` so `x=-2`.
Always CHECK your answers!!
Here's the graph of the function, to help clarify the situation. This time we sketch `y = 10x^-2 + 3x^-1 -1`.
Graph of `y = 10x^-2 + 3x^-1 -1`
The two intersections with the x-axis are at `x = -2` and `x=5`.
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