1.6: Solve cubic equations using a graph

Figure 2 shows the graph of

for $\displaystyle 1\leq x\leq4$, drawn on a grid.

(a) By drawing a suitable straight line on the grid, obtain estimates, to one decimal place, for the roots of

in the interval $\displaystyle 1\leq x\leq4$.

(b) By drawing a suitable straight line on the grid, obtain an estimate, to one decimal place, for the root of

in the interval $\displaystyle 1\leq x\leq4$.