On the grid draw the graph of y=x^3-3x+2

By drawing a suitable straight line on the grid, use your graph to find an estimate for the solution of

2x^3-3x+4=0

Give your answer correct to 1 decimal place

I rearranged equation 2 to give equation 1 on the left hand side, as follows:

x^3-3x+2=-x^3-2

I was expecting this to give a linear equation on the right hand side not a cubic

So plotting the graphs of y=x^3-3x+2 and y=-x^3-2 should give a solution to equation 2

And it does. These two graphs intersect at x=-1.6 which is roughly the solution to equation 2.

But y=-x^3-2 is not a straight line.

Any ideas what straight line they are after??

It’s GCSE so shouldn’t be too complex

Thanks