



 
Hi Sasha, I would stat by drawing a graph of $y = x(x2).$ To invert this function graphically you first interchange the roles of $x$ and $y$ by labeling the Xaxis as the Yaxis and the Yaxis as the Xaxis. Next flip the graph so that the Xaxis is horizontal with positive to the right and the Yaxis vertical with positive upwards. This is a graph of the inverse of $y = x(x2)$ and you can clearly see why it is not a function. For each $x$ value greater than 1 there are two points on the graph with that $x$ value. The instruction "Suggest a domain restriction which would ensure that the inverse is a function." means to suggest a domain restriction on the original function $y = x(x2)$ so that the inverse is a function. For example if you define $y = x(x2)$ for $x \geq 1$ then the graph of this function is and the inverse of this function is a function. I hope this helps,  


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