\includegraphics{figure_1}
Fig. 12 shows the graph of a cubic curve. It intersects the axes at \((-5, 0)\), \((-2, 0)\), \((1.5, 0)\) and \((0, -30)\).
- Use the intersections with both axes to express the equation of the curve in a factorised form. [2]
- Hence show that the equation of the curve may be written as \(y = 2x^3 + 11x^2 - x - 30\). [2]
- Draw the line \(y = 5x + 10\) accurately on the graph. The curve and this line intersect at \((-2, 0)\); find graphically the \(x\)-coordinates of the other points of intersection. [3]
- Show algebraically that the \(x\)-coordinates of the other points of intersection satisfy the equation
$$2x^2 + 7x - 20 = 0.$$
Hence find the exact values of the \(x\)-coordinates of the other points of intersection. [5]