(a(i))[3]
Show that the equation $x^2-40x+A=0$ is obtained.
(a(ii))[3]
Solve, by factorising, the equation $x^2-40x+A=0$ to find the values of $x$.
(a(iii))[4]
Solve the equation $x^2-40x+A=0$ by using the quadratic formula. Show all your working and give your answers correct to 2 decimal places.
(b(i))[3]
Show that the time difference for the two journeys is $\frac{2000}{x(x+10)}$ hours.
(b(ii))[3]
Determine the difference in time between the two journeys when $x=80$. Give your answer in minutes and seconds.