The graphs of \(y=2x^2+x^3-1\) and \(y=x+1\) are drawn on the grid.
Explain why the equation \(2x^2+x^3-1=k\) have 3 solutions for some values of \(k\).[1]
Using the 2 graphs on the grid, find the values of \(a\), \(b\), \(c\) and \(d\) of the inequality \(ax^3+bx^2+cx+d\geq0\) whose solutions are \(-2\leq x\leq-1\) or \(x\geq1\).[2]
Point \(Q\) has coordinates \((-1.6,0.6)\). A tangent to the curve can be drawn so that it passes through point \(Q\).
Find the equation of this tangent in the form \(y=mx+c\), where \(m>0\).[2]