**6.1 - 2016 Q9**

9) Fig. 9 shows the curves

i) Use Fig. 9 to estimate graphically the roots of the equation (2)

ii) Show that the equation in part (i) may be simplified to x

^{3}+ 9x^{2}+ 21x + 13 = 0. Find algebraically the exact roots of this equation. (7)